World Wide Web

The World Wide Web (WWW), commonly known as the Web, is an where documents and other s are identified by  (URLs, such as  https://www.example.com/ ), which may be interlinked by, and are accessible over the. The resources of the WWW may be accessed by users by a called a .

English scientist invented the World Wide Web in 1989. He wrote the first web browser in 1990 while employed at near Geneva, Switzerland. The browser was released outside CERN in 1991, first to other research institutions starting in January 1991 and then to the general public in August 1991. The World Wide Web has been central to the development of the and is the primary tool billions of people use to interact on the Internet.

Web resources may be any type of downloaded media, but s are hypertext media that have been in  (HTML). Such formatting allows for embedded s that contain URLs and permit users to to other web resources. In addition to, web pages may contain s, , , and software components that are in the  web browser as coherent pages of  content.

Multiple web resources with a common theme, a common, or both, make up a. Websites are stored in computers that are running a program called a that responds to requests made over the Internet from web browsers running on a user's computer. Website content can be largely provided by a publisher, or interactively where or the content depends upon the users or their actions. Websites may be provided for a myriad of informative, entertainment, commercial, governmental, or non-governmental reasons.

History
's vision of a global hyperlinked information system became a possibility by the second half of the 1980s. By 1985, the began to proliferate in Europe and the  (upon which the  is built) came into being. In 1988 the first direct IP connection between Europe and North America was made and Berners-Lee began to openly discuss the possibility of a web-like system at CERN.

While working at CERN, Berners-Lee became frustrated with the inefficiencies and difficulties posed by finding information stored on different computers. On March 12, 1989, he submitted a memorandum, titled "Information Management: A Proposal", to the management at CERN for a system called "Mesh" that referenced, a database and software project he had built in 1980, which used the term "web" and described a more elaborate information management system based on links embedded as text: "Imagine, then, the references in this document all being associated with the of the thing to which they referred, so that while reading this document, you could skip to them with a click of the mouse." Such a system, he explained, could be referred to using one of the existing meanings of the word , a term that he says was coined in the 1950s. There is no reason, the proposal continues, why such hypertext links could not encompass multimedia documents including graphics, speech and video, so that Berners-Lee goes on to use the term .

With help from his colleague and fellow hypertext enthusiast he published a more formal proposal on 12 November 1990 to build a "Hypertext project" called "WorldWideWeb" (one word) as a "web" of "hypertext documents" to be viewed by "" using a. At this point HTML and had already been in development for about two months and the first Web server was about a month from completing its first successful test. This proposal estimated that a read-only web would be developed within three months and that it would take six months to achieve "the creation of new links and new material by readers, [so that] authorship becomes universal" as well as "the automatic notification of a reader when new material of interest to him/her has become available". While the read-only goal was met, accessible authorship of web content took longer to mature, with the concept,, s,  and /.

The proposal was modelled after the reader  by Electronic Book Technology, a spin-off from the  at. The Dynatext system, licensed by CERN, was a key player in the extension of SGML ISO 8879:1986 to Hypermedia within, but it was considered too expensive and had an inappropriate licensing policy for use in the general high energy physics community, namely a fee for each document and each document alteration. A was used by Berners-Lee as the world's first  and also to write the first, , in 1990. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web: the (which was a web editor as well) and the first web server. The first web site, which described the project itself, was published on 20 December 1990.

The first web page may be lost, but of  in North Carolina announced in May 2013 that Berners-Lee gave him what he says is the oldest known web page during a 1991 visit to UNC. Jones stored it on a and on his NeXT computer. On 6 August 1991, Berners-Lee published a short summary of the World Wide Web project on the alt.hypertext. This date is sometimes confused with the public availability of the first web servers, which had occurred months earlier. As another example of such confusion, several news media reported that the first photo on the Web was published by Berners-Lee in 1992, an image of the CERN house band taken by Silvano de Gennaro; Gennaro has disclaimed this story, writing that media were "totally distorting our words for the sake of cheap sensationalism".

The first server outside Europe was installed at the (SLAC) in Palo Alto, California, to host the -HEP database. Accounts differ substantially as to the date of this event. The World Wide Web Consortium's timeline says December 1992, whereas SLAC itself claims December 1991, as does a W3C document titled A Little History of the World Wide Web. The underlying concept of hypertext originated in previous projects from the 1960s, such as the (HES) at Brown University, 's, and 's  (NLS). Both Nelson and Engelbart were in turn inspired by 's -based , which was described in the 1945 essay "".

Berners-Lee's breakthrough was to marry hypertext to the Internet. In his book , he explains that he had repeatedly suggested that a marriage between the two technologies was possible to members of both technical communities, but when no one took up his invitation, he finally assumed the project himself. In the process, he developed three essential technologies:
 * a system of globally unique identifiers for resources on the Web and elsewhere, the universal document identifier (UDI), later known as (URL) and  (URI);
 * the publishing language (HTML);
 * the (HTTP).

The World Wide Web had several differences from other hypertext systems available at the time. The Web required only unidirectional links rather than bidirectional ones, making it possible for someone to link to another resource without action by the owner of that resource. It also significantly reduced the difficulty of implementing web servers and browsers (in comparison to earlier systems), but in turn presented the chronic problem of . Unlike predecessors such as, the World Wide Web was non-proprietary, making it possible to develop servers and clients independently and to add extensions without licensing restrictions. On 30 April 1993, CERN announced that the World Wide Web would be free to anyone, with no fees due. Coming two months after the announcement that the server implementation of the protocol was no longer free to use, this produced a rapid shift away from Gopher and towards the Web. An early popular web browser was for  and the.

Scholars generally agree that a turning point for the World Wide Web began with the introduction of the web browser in 1993, a graphical browser developed by a team at the  at the  (NCSA-UIUC), led by. Funding for Mosaic came from the US High-Performance Computing and Communications Initiative and the, one of. Prior to the release of Mosaic, graphics were not commonly mixed with text in web pages and the web's popularity was less than that of older protocols in use over the Internet, such as and  (WAIS). Mosaic's graphical user interface allowed the Web to become, by far, the most popular Internet protocol. The (W3C) was founded by Tim Berners-Lee after he left the European Organization for Nuclear Research (CERN) in October 1994. It was founded at the Laboratory for Computer Science (MIT/LCS) with support from the  (DARPA), which had pioneered the Internet; a year later, a second site was founded at  (a French national computer research lab) with support from the  DG InfSo; and in 1996, a third continental site was created in Japan at. By the end of 1994, the total number of websites was still relatively small, but many were already active that foreshadowed or inspired today's most popular services.

Connected by the Internet, other websites were created around the world. This motivated international standards development for protocols and formatting. Berners-Lee continued to stay involved in guiding the development of web standards, such as the s to compose web pages and he advocated his vision of a. The World Wide Web enabled the spread of information over the Internet through an easy-to-use and flexible format. It thus played an important role in popularising use of the Internet. Although the two terms are sometimes in popular use, World Wide Web is not ous with Internet. The Web is an containing hyperlinked documents and other, identified by their URIs. It is implemented as both client and server software using Internet protocols such as and. Berners-Lee was in 2004 by Queen  for "services to the global development of the Internet". He never patented his invention.

Function
The terms Internet and World Wide Web are often used without much distinction. However, the two terms do not mean the same thing. The Internet is a global system of interconnected s. In contrast, the World Wide Web is a global collection of documents and other, linked by hyperlinks and. Web resources are accessed using or, which are application-level Internet protocols that use the Internet's transport protocols.

Viewing a on the World Wide Web normally begins either by typing the  of the page into a web browser, or by following a hyperlink to that page or resource. The web browser then initiates a series of background communication messages to fetch and display the requested page. In the 1990s, using a browser to view web pages—and to move from one web page to another through hyperlinks—came to be known as 'browsing,' 'web surfing' (after ), or 'navigating the Web'. Early studies of this new behaviour investigated user patterns in using web browsers. One study, for example, found five user patterns: exploratory surfing, window surfing, evolved surfing, bounded navigation and targeted navigation.

The following example demonstrates the functioning of a web browser when accessing a page at the URL. The browser resolves the server name of the URL into an  using the globally distributed  (DNS). This lookup returns an IP address such as 203.0.113.4 or 2001:db8:2e::7334. The browser then requests the resource by sending an request across the Internet to the computer at that address. It requests service from a specific TCP port number that is well known for the HTTP service, so that the receiving host can distinguish an HTTP request from other network protocols it may be servicing. The HTTP protocol normally uses and for HTTPS protocol it normally is. The content of the HTTP request can be as simple as two lines of text:

The computer receiving the HTTP request delivers it to web server software listening for requests on port 80. If the web server can fulfil the request it sends an HTTP response back to the browser indicating success:

followed by the content of the requested page. HyperText Markup Language for a basic web page might look like this:

The web browser the HTML and interprets the markup (,   for paragraph, and such) that surrounds the words to format the text on the screen. Many web pages use HTML to reference the URLs of other resources such as images, other embedded media, that affect page behaviour, and  that affect page layout. The browser makes additional HTTP requests to the web server for these other s. As it receives their content from the web server, the browser progressively the page onto the screen as specified by its HTML and these additional resources.

HTML
Hypertext Markup Language (HTML) is the standard for creating s and s. With  (CSS) and, it forms a triad of  technologies for the World Wide Web.

s receive HTML documents from a or from local storage and  the documents into multimedia web pages. HTML describes the structure of a web page and originally included cues for the appearance of the document.

s are the building blocks of HTML pages. With HTML constructs, and other objects such as  may be embedded into the rendered page. HTML provides a means to create s by denoting structural for text such as headings, paragraphs, lists,, quotes and other items. HTML elements are delineated by tags, written using. Tags such as and  directly introduce content into the page. Other tags such as surround and provide information about document text and may include other tags as sub-elements. Browsers do not display the HTML tags, but use them to interpret the content of the page.

HTML can embed programs written in a such as, which affects the behavior and content of web pages. Inclusion of CSS defines the look and layout of content. The (W3C), maintainer of both the HTML and the CSS standards, has encouraged the use of CSS over explicit presentational HTML

Linking
Most web pages contain hyperlinks to other related pages and perhaps to downloadable files, source documents, definitions and other web resources. In the underlying HTML, a hyperlink looks like this:

Such a collection of useful, related resources, interconnected via hypertext links is dubbed a web of information. Publication on the Internet created what Tim Berners-Lee first called the WorldWideWeb (in its original, which was subsequently discarded) in November 1990.

The hyperlink structure of the WWW is described by the : the nodes of the web graph correspond to the web pages (or URLs) the directed edges between them to the hyperlinks. Over time, many web resources pointed to by hyperlinks disappear, relocate, or are replaced with different content. This makes hyperlinks obsolete, a phenomenon referred to in some circles as link rot, and the hyperlinks affected by it are often called s. The ephemeral nature of the Web has prompted many efforts to archive web sites. The, active since 1996, is the best known of such efforts.

WWW prefix
Many hostnames used for the World Wide Web begin with www because of the long-standing practice of naming hosts according to the services they provide. The of a  is often www, in the same way that it may be ftp for an, and news or nntp for a. These host names appear as Domain Name System (DNS) or names, as in www.example.com. The use of www is not required by any technical or policy standard and many web sites do not use it; the first web server was nxoc01.cern.ch. According to Paolo Palazzi, who worked at CERN along with Tim Berners-Lee, the popular use of www as subdomain was accidental; the World Wide Web project page was intended to be published at www.cern.ch while info.cern.ch was intended to be the CERN home page, however the DNS records were never switched, and the practice of prepending www to an institution's website domain name was subsequently copied. Many established websites still use the prefix, or they employ other subdomain names such as www2, secure or en for special purposes. Many such web servers are set up so that both the main domain name (e.g., example.com) and the www subdomain (e.g., www.example.com) refer to the same site; others require one form or the other, or they may map to different web sites. The use of a subdomain name is useful for incoming web traffic by creating a  that points to a cluster of web servers. Since, currently, only a subdomain can be used in a CNAME, the same result cannot be achieved by using the bare domain root.

When a user submits an incomplete domain name to a web browser in its address bar input field, some web browsers automatically try adding the prefix "www" to the beginning of it and possibly ".com", ".org" and ".net" at the end, depending on what might be missing. For example, entering 'microsoft' may be transformed to  http://www.microsoft.com/  and 'openoffice' to  http://www.openoffice.org . This feature started appearing in early versions of, when it still had the working title 'Firebird' in early 2003, from an earlier practice in browsers such as. It is reported that Microsoft was granted a US patent for the same idea in 2008, but only for mobile devices.

In English, double-u double-u double-u. Some users pronounce it dub-dub-dub, particularly in New Zealand. Stephen Fry, in his "Podgrams" series of podcasts, pronounces it wuh wuh wuh. The English writer once quipped in  on Sunday (1999): "The World Wide Web is the only thing I know of whose shortened form takes three times longer to say than what it's short for". In Mandarin Chinese, World Wide Web is commonly translated via a to wàn wéi wǎng, which satisfies www and literally means "myriad dimensional net", a translation that reflects the design concept and proliferation of the World Wide Web. Tim Berners-Lee's web-space states that World Wide Web is officially spelled as three separate words, each capitalised, with no intervening hyphens. Use of the www prefix has been declining, especially when s sought to brand their domain names and make them easily pronounceable. As the grew in popularity, services like .com,, .com, .com and .com are most often mentioned without adding "www." (or, indeed, ".com") to the domain.

Scheme specifiers
The scheme specifiers   and   at the start of a web refer to  or, respectively. They specify the communication protocol to use for the request and response. The HTTP protocol is fundamental to the operation of the World Wide Web, and the added encryption layer in HTTPS is essential when browsers send or retrieve confidential data, such as passwords or banking information. Web browsers usually automatically prepend http:// to user-entered URIs, if omitted.

Web page
A web page (also written as webpage) is a document that is suitable for the World Wide Web and s. A web browser displays a web page on a or.

The term web page usually refers to what is visible, but may also refer to the contents of the itself, which is usually a  containing  written in  or a comparable. Typical web pages provide for browsing to other web pages via s, often referred to as links. Web browsers will frequently have to access multiple elements, such as reading, , and images, while presenting each web page.

On a network, a web browser can retrieve a web page from a remote. The web server may restrict access to a private network such as a corporate intranet. The web browser uses the (HTTP) to make such requests to the.

A is delivered exactly as stored, as  in the web server's. In contrast, a is generated by a, usually driven by. Dynamic web pages help the browser (the ) to enhance the web page through user input to the server.

Static web page
A static web page (sometimes called a flat page/stationary page) is a that is delivered to the user exactly as stored, in contrast to s which are generated by a.

Consequently, a static web page displays the same information for all users, from all contexts, subject to modern capabilities of a to   or language of the document where such versions are available and the server is configured to do so.

Dynamic web pages
A server-side dynamic web page is a whose construction is controlled by an  processing server-side scripts. In server-side scripting, determine how the assembly of every new web page proceeds, including the setting up of more client-side processing.

A client-side dynamic web page processes the web page using running in the browser as it loads. JavaScript and other scripting languages determine the way the HTML in the received page is parsed into the, or DOM, that represents the loaded web page. The same client-side techniques can then dynamically update or change the DOM in the same way.

A dynamic web page is then reloaded by the user or by a to change some variable content. The updating information could come from the server, or from changes made to that page's DOM. This may or may not truncate the browsing history or create a saved version to go back to, but a dynamic web page update using technologies will neither create a page to go back to, nor truncate the  forward of the displayed page. Using Ajax technologies the end gets one dynamic page managed as a single page in the  while the actual  rendered on that page can vary. The Ajax engine sits only on the browser requesting parts of its DOM, the DOM, for its client, from an application server.

is the umbrella term for technologies and methods used to create web pages that are not s, though it has fallen out of common use since the popularization of, a term which is now itself rarely used. Client-side-scripting, server-side scripting, or a combination of these make for the dynamic web experience in a browser.

is a that was initially developed in 1995 by, then of , for use within web pages. The standardised version is. To make web pages more interactive, some web applications also use JavaScript techniques such as ( JavaScript and ). is delivered with the page that can make additional HTTP requests to the server, either in response to user actions such as mouse movements or clicks, or based on elapsed time. The server's responses are used to modify the current page rather than creating a new page with each response, so the server needs only to provide limited, incremental information. Multiple Ajax requests can be handled at the same time, and users can interact with the page while data is retrieved. Web pages may also regularly the server to check whether new information is available.

Website
A website is a collection of related web resources including s, content, typically identified with a common, and published on at least one. Notable examples are .org, .com, and.

A website may be accessible via a public (IP) network, such as the, or a private  (LAN), by referencing a  (URL) that identifies the site.

Websites can have many functions and can be used in various fashions; a website can be a, a corporate website for a company, a government website, an organization website, etc. Websites are typically dedicated to a particular topic or purpose, ranging from entertainment and to providing news and education. All publicly accessible websites collectively constitute the World Wide Web, while private websites, such as a company's website for its employees, are typically a part of an.

Web pages, which are the building blocks of websites, are s, typically composed in interspersed with formatting instructions of Hypertext Markup Language. They may incorporate elements from other websites with suitable. Web pages are accessed and transported with the (HTTP), which may optionally employ encryption (, HTTPS) to provide security and privacy for the user. The user's application, often a, renders the page content according to its HTML markup instructions onto a.

ing between web pages conveys to the reader the and guides the navigation of the site, which often starts with a  containing a directory of the site. Some websites require user registration or to access content. Examples of include many business sites, news websites,  websites, gaming websites, file-sharing websites,, web-based ,  websites, websites providing real-time  data, as well as sites providing various other services. s can access websites on a range of devices, including and, s, s and s.

Web browser
A web browser (commonly referred to as a browser) is a  for accessing information on the World Wide Web. To connect to a website's and display its pages, a user needs to have a web browser program. This is the program that the user runs to download, format and display a web page on the user's computer.

In addition to allowing users to find, displaying and moving between web pages, a web browser will usually have features like keeping bookmarks, recording history, managing cookies (see below) and home pages and may have facilities for recording passwords for logging into web sites.

The most popular browsers are, , , , and.

Web server
A Web server is, or hardware dedicated to running said software, that can satisfy World Wide Web client requests. A web server can, in general, contain one or more websites. A web server processes incoming network requests over and several other related protocols.

The primary function of a web server is to store, process and deliver s to. The communication between client and server takes place using the. Pages delivered are most frequently, which may include s, and  in addition to the text content.

A, commonly a or , initiates communication by making a  for a specific resource using HTTP and the server responds with the content of that resource or an  if unable to do so. The resource is typically a real file on the server's, but this is not necessarily the case and depends on how the web server is.

While the primary function is to serve content, a full implementation of HTTP also includes ways of receiving content from clients. This feature is used for submitting, including ing of files.

Many generic web servers also support using  (ASP),  (Hypertext Preprocessor), or other s. This means that the behaviour of the web server can be scripted in separate files, while the actual server software remains unchanged. Usually, this function is used to generate HTML documents ("on-the-fly") as opposed to returning. The former is primarily used for retrieving or modifying information from s. The latter is typically much faster and more easily but cannot deliver.

Web servers can also frequently be found in devices such as, , s and serving only a. The web server may then be used as a part of a system for monitoring or administering the device in question. This usually means that no additional software has to be installed on the client computer since only a web browser is required (which now is included with most s).

HTTP (web) cookie
An HTTP cookie (also called web cookie, Internet cookie, browser cookie, or simply cookie) is a small piece of data sent from a website and stored on the user's computer by the user's while the user is browsing. Cookies were designed to be a reliable mechanism for websites to remember information (such as items added in the shopping cart in an online store) or to record the user's browsing activity (including clicking particular buttons,, or recording which pages were visited in the past). They can also be used to remember arbitrary pieces of information that the user previously entered into form fields such as names, addresses, passwords, and credit card numbers.

Cookies perform essential functions in the modern web. Perhaps most importantly, authentication cookies are the most common method used by web servers to know whether the user is logged in or not, and which account they are logged in with. Without such a mechanism, the site would not know whether to send a page containing sensitive information, or require the user to authenticate themselves by logging in. The security of an authentication cookie generally depends on the security of the issuing website and the user's, and on whether the cookie data is encrypted. Security vulnerabilities may allow a cookie's data to be read by a, used to gain access to user data, or used to gain access (with the user's credentials) to the website to which the cookie belongs (see and  for examples).

Tracking cookies, and especially, are commonly used as ways to compile long-term records of individuals' browsing histories – a potential that prompted European and U.S. lawmakers to take action in 2011. European law requires that all websites targeting member states gain "informed consent" from users before storing non-essential cookies on their device.

Google researcher Jann Horn describes ways cookies can be read by, like  hotspot providers. He recommends to use the browser in in such circumstances.

Search engine
A web search engine or Internet search engine is a that is designed to carry out web search (Internet search), which means to search the World Wide Web in a systematic way for particular information specified in a. The search results are generally presented in a line of results, often referred to as s (SERPs). The information may be a mix of s, images, videos, infographics, articles, research papers and other types of files. Some search engines also available in s or. Unlike, which are maintained only by human editors, search engines also maintain information by running an  on a. Internet content that is not capable of being searched by a web search engine is generally described as the.

Deep web
The deep web, invisible web, or hidden web are parts of the World Wide Web whose contents are not by standard s. The opposite term to the deep web is the, which is accessible to anyone using the Internet. Michael K. Bergman is credited with coining the term deep web in 2001 as a search indexing term.

The content of the deep web is hidden behind forms, and includes many very common uses such as, , and services that users must pay for, and which is protected by a , such as , some online magazines and newspapers, among others.

The content of the deep web can be located and accessed by a direct or, and may require a password or other security access past the public website page.

Web caching
A is a server computer located either on the public Internet, or within an enterprise that stores recently accessed web pages to improve response time for users when the same content is requested within a certain time after the original request. Most web browsers also implement a by writing recently obtained data to a local data storage device. HTTP requests by a browser may ask only for data that has changed since the last access. Web pages and resources may contain expiration information to control caching to secure sensitive data, such as in, or to facilitate frequently updated sites, such as news media. Even sites with highly dynamic content may permit basic resources to be refreshed only occasionally. Web site designers find it worthwhile to collate resources such as CSS data and JavaScript into a few site-wide files so that they can be cached efficiently. Enterprise often cache Web resources requested by one user for the benefit of many users. Some store cached content of frequently accessed websites.

Web security
For s, the Web has become a venue to spread and engage in a range of s, including, ,  and. Web-based now outnumber traditional computer security concerns, and as measured by, about one in ten web pages may contain malicious code. Most web-based take place on legitimate websites, and most, as measured by, are hosted in the United States, China and Russia. The most common of all malware is  attacks against websites. Through HTML and URIs, the Web was vulnerable to attacks like (XSS) that came with the introduction of JavaScript and were exacerbated to some degree by  and Ajax  that favours the use of scripts. Today by one estimate, 70% of all websites are open to XSS attacks on their users. is another common threat to the Web. In February 2013, RSA (the security division of EMC) estimated the global losses from phishing at $1.5 billion in 2012. Two of the well-known phishing methods are Covert Redirect and Open Redirect.

Proposed solutions vary. Large security companies like already design governance and compliance suites to meet post-9/11 regulations, and some, like  have recommended active real-time inspection of programming code and all content regardless of its source. Some have argued that for enterprises to see Web security as a business opportunity rather than a, while others call for "ubiquitous, always-on " enforced in the infrastructure to replace the hundreds of companies that secure data and networks. has said users sharing responsibility for computing safety is far preferable to locking down the Internet.

Privacy
Every time a client requests a web page, the server can identify the request's IP address and usually logs it. Also, unless set not to do so, most web browsers record requested web pages in a viewable history feature, and usually much of the content locally. Unless the server-browser communication uses HTTPS encryption, web requests and responses travel in plain text across the Internet and can be viewed, recorded, and cached by intermediate systems. Another way to hide is by using a. A VPN online traffic and masks original IP address lowering the chance of user identification. When a web page asks for, and the user supplies, personally identifiable information—such as their real name, address, e-mail address, etc.—web-based entities can associate current web traffic with that individual. If the website uses s, username and password authentication, or other tracking techniques, it can relate other web visits, before and after, to the identifiable information provided. In this way it is possible for a web-based organisation to develop and build a profile of the individual people who use its site or sites. It may be able to build a record for an individual that includes information about their leisure activities, their shopping interests, their profession, and other aspects of their. These profiles are obviously of potential interest to marketeers, advertisers and others. Depending on the website's and the local laws that apply information from these profiles may be sold, shared, or passed to other organisations without the user being informed. For many ordinary people, this means little more than some unexpected e-mails in their in-box or some uncannily relevant advertising on a future web page. For others, it can mean that time spent indulging an unusual interest can result in a deluge of further targeted marketing that may be unwelcome. Law enforcement, counter terrorism, and espionage agencies can also identify, target and track individuals based on their interests or proclivities on the Web.

sites try to get users to use their real names, interests, and locations, rather than pseudonyms, as their executives believe that this makes the social networking experience more engaging for users. On the other hand, uploaded photographs or unguarded statements can be identified to an individual, who may regret this exposure. Employers, schools, parents, and other relatives may be influenced by aspects of social networking profiles, such as text posts or digital photos, that the posting individual did not intend for these audiences. may make use of personal information to harass or users. Modern social networking websites allow fine grained control of the privacy settings for each individual posting, but these can be complex and not easy to find or use, especially for beginners. Photographs and videos posted onto websites have caused particular problems, as they can add a person's face to an on-line profile. With modern and potential, it may then be possible to relate that face with other, previously anonymous, images, events and scenarios that have been imaged elsewhere. Due to image caching, mirroring and copying, it is difficult to remove an image from the World Wide Web.

Standards
Web standards include many interdependent standards and specifications, some of which govern aspects of the, not just the World Wide Web. Even when not web-focused, such standards directly or indirectly affect the development and administration of web sites and s. Considerations include the, and  of web pages and web sites.

Web standards, in the broader sense, consist of the following:
 * Recommendations published by the (W3C)
 * "Living Standard" made by the (WHATWG)
 *  (RFC) documents published by the (IETF)
 * Standards published by the (ISO)
 * Standards published by (formerly ECMA)
 * The Standard and various Unicode Technical Reports (UTRs) published by the
 * Name and number registries maintained by the (IANA)

Web standards are not fixed sets of rules, but are a constantly evolving set of finalized technical specifications of web technologies. Web standards are developed by s—groups of interested and often competing parties chartered with the task of standardization—not technologies developed and declared to be a standard by a single individual or company. It is crucial to distinguish those specifications that are under development from the ones that already reached the final development status (in case of specifications, the highest maturity level).

Accessibility
There are methods for accessing the Web in alternative mediums and formats to facilitate use by individuals with. These disabilities may be visual, auditory, physical, speech-related, cognitive, neurological, or some combination. Accessibility features also help people with temporary disabilities, like a broken arm, or ageing users as their abilities change. The Web receives information as well as providing information and interacting with society. The World Wide Web Consortium claims that it is essential that the Web be accessible, so it can provide equal access and to people with disabilities. Tim Berners-Lee once noted, "The power of the Web is in its universality. Access by everyone regardless of disability is an essential aspect." Many countries regulate as a requirement for websites. International co-operation in the W3C led to simple guidelines that web content authors as well as software developers can use to make the Web accessible to persons who may or may not be using.

Internationalisation
The W3C Activity assures that web technology works in all languages, scripts, and cultures. Beginning in 2004 or 2005, gained ground and eventually in December 2007 surpassed both  and Western European as the Web's most frequently used. Originally allowed resources to be identified by  in a subset of US-ASCII. allows more characters—any character in the —and now a resource can be identified by in any language.