What Is the World Wide Web?

The World Wide Web is a global information system built on interconnected hypertext documents and other resources, accessible through the Internet via standardized protocols and addressed by uniform resource identifiers (URIs). It is distinct from the Internet itself: the Internet is the underlying network infrastructure of connected computers and communication links, while the Web is an application layer that runs on top of that infrastructure, using the Internet's transport mechanisms to deliver documents, media, and interactive services to users worldwide.

Tim Berners-Lee invented the Web in 1989 while working at CERN, the European particle physics laboratory. His original proposal described a distributed information management system to help scientists share data across institutional boundaries. By December 1990, the first web server and browser were running at CERN, and Berners-Lee had defined the three foundational technologies that remain central to the Web: HyperText Markup Language (HTML) for document formatting, the HyperText Transfer Protocol (HTTP) for client-server communication, and the uniform resource locator (URL) as the standard addressing scheme.

Core Technologies

HTML defines the structure and semantics of web documents through a system of markup tags. A browser parses HTML to construct a document object model (DOM), which it then renders visually. Cascading Style Sheets (CSS) separate visual presentation from document structure, and JavaScript enables dynamic behavior within the browser. Together, these three technologies form the client-side stack that powers modern websites.

HTTP is the application-layer protocol through which browsers request resources from web servers and servers deliver responses. HTTP/1.1, introduced in 1997, added persistent connections and chunked transfer encoding. HTTP/2 (2015) and HTTP/3 (2022) introduced multiplexing and QUIC-based transport, respectively, reducing latency for pages that require many simultaneous resource fetches. The W3C, which Berners-Lee founded in 1994, maintains many of the Web's core specifications including HTML and CSS, coordinating standardization across browser vendors and platform developers.

Web Architecture and Browsers

The Web operates on a client-server architecture. A browser acting as the client issues an HTTP request to a server identified by a URL. The server responds with the requested resource, typically an HTML document that references additional assets (images, scripts, stylesheets) which the browser fetches in subsequent requests. Dynamic web applications use server-side frameworks to assemble responses from databases and business logic, or shift that assembly to the browser via JavaScript frameworks that communicate with APIs.

Search engines index the Web by crawling hyperlinks between pages, and their ranking algorithms determine which documents appear in response to a user query. The graph structure of the Web, in which pages link to related pages, was foundational to Google's PageRank algorithm, which treated inbound links as votes of relevance. Content delivery networks (CDNs) cache copies of resources at geographically distributed edge servers to reduce latency for globally distributed users.

Web Sites and the Modern Web

Web sites range from static pages consisting of fixed HTML files to complex web applications that dynamically assemble content based on user authentication, preferences, and real-time data. The Web has expanded well beyond documents and text: streaming video, interactive maps, collaborative editing, and e-commerce checkout flows are all delivered through browser-based interfaces. The W3C Web Accessibility Initiative publishes the Web Content Accessibility Guidelines (WCAG), which establish standards for making web content usable by people with disabilities, reflecting the Web's role as a critical public information infrastructure.

Applications

The World Wide Web has applications in a wide range of fields, including:

• Scientific publishing and open-access distribution of research findings
• E-commerce, online banking, and digital financial services
• Government services, open data portals, and civic information
• Distance education and online learning platforms
• Social communication, media distribution, and collaborative knowledge creation