HistoryThe underlying concept of hypertext originated in previous projects from the 1960s, such as the Hypertext Editing System (HES) at Brown University, Ted Nelson's Project Xanadu, and Douglas Engelbart's NLS (computer system), oN-Line System (NLS). Both Nelson and Engelbart were in turn inspired by Vannevar Bush's microfilm-based ''memex'', which was described in the 1945 essay "As We May Think". Tim Berners-Lee's vision of a global hyperlinked information system became a possibility by the second half of the 1980s. By 1985, the Global Internet usage, global Internet began to proliferate in Europe and the Domain Name System (upon which the Uniform Resource Locator 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 12 March 1989, he submitted a memorandum, titled "Information Management: A Proposal", to the management at CERN for a system called "Mesh" that referenced ENQUIRE, 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 network address 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 ''hypertext'', 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 ''hypermedia''. With help from his colleague and fellow hypertext enthusiast Robert Cailliau he published a more formal proposal on 12 November 1990 to build a "Hypertext project" called "WorldWideWeb" (one word, abbreviated 'W3') as a "web" of "hypertext documents" to be viewed by "Web browser, browsers" using a client–server architecture.He Created the Web. Now He’s Out to Remake the Digital World.
FunctionThe 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 computer networks. In contrast, the World Wide Web is a global collection of documents and other Web resource, resources, linked by hyperlinks and Uniform Resource Identifier, URIs. Web resources are accessed using HTTP or HTTPS, 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 uniform resource locator, URL 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 channel surfing), 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 IP address, Internet Protocol address using the globally distributed Domain Name System (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 Hypertext Transfer Protocol, HTTP 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. HTTP normally uses List of TCP and UDP port numbers, port number 80 and for HTTPS it normally uses List of TCP and UDP port numbers, port number 443. The content of the HTTP request can be as simple as two lines of text:
The World Wide Web, abbreviated as WWW and commonly known ...
LinkingMost 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:
WWW prefixMany 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 hostname of a is often ''www'', in the same way that it may be ''ftp'' for an FTP server, and ''news'' or ''nntp'' for a Usenet news server. These host names appear as Domain Name System (DNS) or subdomain 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 load balancing (computing), load balancing incoming web traffic by creating a CNAME record 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 '' may be transformed to ''
Scheme specifiersThe scheme specifiers ''
'' and ''
'' at the start of a web Uniform Resource Identifier, URI refer to or HTTP Secure, 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
PagesA ''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 computer display, monitor or mobile device. The term ''web page'' usually refers to what is visible, but may also refer to the contents of the computer file itself, which is usually a text file containing hypertext written in HTML or a comparable markup language. Typical web pages provide hypertext for browsing to other web pages via hyperlinks, often referred to as ''links''. Web browsers will frequently have to access multiple web resource elements, such as reading Cascading Style Sheets, style sheets, client-side scripting, scripts, 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 static web page, ''static'' web page is delivered exactly as stored, as web content in the web server's file system. In contrast, a dynamic web page, ''dynamic'' web page is generated by a web application, usually driven by server-side scripting, server-side software. Dynamic web pages are used when each user may require completely different information, for example, bank websites, web email etc.
Static pageA ''static web page'' (sometimes called a ''flat page/stationary page'') is a that is delivered to the user exactly as stored, in contrast to dynamic web pages which are generated by a web application. Consequently, a static web page displays the same information for all users, from all contexts, subject to modern capabilities of a to content negotiation, negotiate MIME type, content-type or language of the document where such versions are available and the server is configured to do so.
WebsiteA ''website'' is a collection of related web resources including s, multimedia content, typically identified with a common domain name, and published on at least one . Notable examples are wikipedia, wikipedia.org, google, google.com, and Amazon (company), amazon.com. A website may be accessible via a public Internet Protocol (IP) network, such as the , or a private local area network (LAN), by referencing a URL, uniform resource locator (URL) that identifies the site. Websites can have many functions and can be used in various fashions; a website can be a personal website, 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 social networking 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 intranet. Web pages, which are the building blocks of websites, are documents, typically composed in plain text interspersed with formatting instructions of Hypertext Markup Language (HTML, XHTML). They may incorporate elements from other websites with suitable HTML anchor, markup anchors. Web pages are accessed and transported with the (HTTP), which may optionally employ encryption (HTTP Secure, 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 Computer monitor, display terminal. Hyperlinking between web pages conveys to the reader the site map, site structure and guides the navigation of the site, which often starts with a home page containing a directory of the site web content. Some websites require user registration or subscription to access content. Examples of paywall, subscription websites include many business sites, news websites, academic journal websites, gaming websites, file-sharing websites, Internet forum, message boards, web-based email, social networking websites, websites providing real-time stock market data, as well as sites providing various other services. End users can access websites on a range of devices, including desktop computer, desktop and laptop, laptop computers, tablet computers, smartphones and smart TVs.
BrowserA ''web browser'' (commonly referred to as a ''browser'') is a software application, software user agent for accessing information on the World Wide Web. To connect to a website's web server, server 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 Google Chrome, Chrome, Firefox, Safari (web browser), Safari, Internet Explorer, and Microsoft Edge, Edge.
CookieAn ''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 program state, stateful 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, access control, logging in, 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 comparison of web browsers#Vulnerabilities, web browser, and on whether the cookie data is encrypted. Security vulnerabilities may allow a cookie's data to be read by a hacker (computer security), hacker, 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 cross-site scripting and cross-site request forgery for examples). Tracking cookies, and especially #Third-party cookie, third-party tracking cookies, are commonly used as ways to compile long-term records of individuals' browsing histories a potential Internet privacy#HTTP cookies, privacy concern that prompted European and U.S. lawmakers to take action in 2011. European law requires that all websites targeting European Union member states gain "informed consent" from users before storing non-essential cookies on their device. Google Project Zero (Google), Project Zero researcher Jann Horn describes ways cookies can be read by Man-in-the-middle attack, intermediaries, like Wi-Fi hotspot providers. He recommends to use the browser in incognito mode in such circumstances.
Search engineA ''web search engine'' or ''Internet search engine'' is a software system 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 web search query. The search results are generally presented in a line of results, often referred to as search engine results pages (SERPs). The information may be a mix of s, images, videos, infographics, articles, research papers and other types of files. Some search engines also data mining, mine data available in databases or web directory, open directories. Unlike web directories, which are maintained only by human editors, search engines also maintain real-time computing, real-time information by running an algorithm on a web crawler. Internet content that is not capable of being searched by a web search engine is generally described as the deep web.
Deep webThe deep web, ''invisible web'', or ''hidden web'' are parts of the World Wide Web whose contents are not Search engine indexing, indexed by standard web search engines. The opposite term to the deep web is the surface web, which is accessible to anyone using the Internet. Computer science, Computer scientist 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 HTTP forms, and includes many very common uses such as web mail, online banking, and services that users must pay for, and which is protected by a paywall, such as video on demand, some online magazines and newspapers, among others. The content of the deep web can be located and accessed by a direct URL or IP address, and may require a password or other security access past the public website page.
PrivacyEvery time a client requests a web page, the server can identify the request's IP address. Web servers usually log IP addresses in a log file. Also, unless set not to do so, most web browsers record requested web pages in a viewable ''history'' feature, and usually Web cache, cache 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 personally identifiable information is by using a virtual private network. A VPN encryption, encrypts online traffic and masks the 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 HTTP cookies, 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 organization 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 demographic profile. These profiles are obviously of potential interest to marketers, advertisers, and others. Depending on the website's terms and conditions and the local laws that apply information from these profiles may be sold, shared, or passed to other organizations 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. Social networking sites usually 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. Cyberbullying, Online bullies may make use of personal information to harass or cyberstalking, stalk 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 Facial recognition system, facial recognition technology, 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.
StandardsWeb 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 web services. Considerations include the interoperability, accessibility and usability of web pages and web sites. Web standards, in the broader sense, consist of the following: * ''Recommendations'' published by the World Wide Web Consortium (W3C) * "Living Standard" made by the Web Hypertext Application Technology Working Group (WHATWG) * ''Request for Comments'' (RFC) documents published by the Internet Engineering Task Force (IETF) * ''Standards'' published by the International Organization for Standardization (ISO) * ''Standards'' published by Ecma International (formerly ECMA) * ''The Unicode Standard'' and various ''Unicode Technical Reports'' (UTRs) published by the Unicode Consortium * Name and number registries maintained by the Internet Assigned Numbers Authority (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 standards organizations—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 W3C specifications, the highest maturity level).
AccessibilityThere are methods for accessing the Web in alternative mediums and formats to facilitate use by individuals with disability, disabilities. 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 equal opportunity 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 web accessibility as a requirement for websites. International co-operation in the W3C Web Accessibility Initiative 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 assistive technology.
InternationalisationThe W3C Internationalization and localization, Internationalisation Activity assures that web technology works in all languages, scripts, and cultures. Beginning in 2004 or 2005, Unicode gained ground and eventually in December 2007 surpassed both ASCII and Western European as the Web's most frequently used character encoding. Originally allowed resources to be identified by URI in a subset of US-ASCII. allows more characters—any character in the Universal Character Set—and now a resource can be identified by Internationalized Resource Identifier, IRI in any language.
See also* Electronic publishing * Internet metaphors * Internet security * Lists of websites * Prestel * Streaming media * Web development tools * Web literacy * World Wide Telecom Web
Further reading* * * * Niels Brügger, ed. ''Web History'' (2010) 362 pages; Historical perspective on the World Wide Web, including issues of culture, content, and preservation. * * Skau, H.O. (March 1990). "The World Wide Web and Health Information". ''New Devices''.