The World Wide Web is a distributed information system that uses Internet connectivity and standardised technologies to publish and access interlinked resources. It was proposed by Tim Berners-Lee at CERN in 1989, with the first implementation developed around 1990. Its foundational technologies included HTML for document structure, HTTP for transferring resources and URLs, now generally discussed within the broader URI framework, for identifying resources. The Web transformed networked information from a collection of separately accessed services into a system in which documents and resources could be linked through hyperlinks. A web browser interprets web resources and provides an interface through which users can navigate between them.
The Web operates primarily through a client-server model. A browser acts as a client and sends requests to web servers, while servers return resources or dynamically generated responses. HTTP defines request and response semantics, methods such as GET and POST, status codes and headers. HTTPS is HTTP carried over a TLS-protected connection, providing encryption and server authentication when correctly configured. Modern Web applications can also use persistent or multiplexed connections and browser APIs for interactive functionality. The Web therefore encompasses both simple hypertext documents and sophisticated applications that execute substantial amounts of code in the browser while communicating with distributed backend systems.
HTML, CSS and JavaScript are often described as the core technologies of the modern Web, although the Web ecosystem contains many additional standards. HTML defines document structure and semantics, CSS controls presentation and layout, and JavaScript provides general-purpose client-side programming and interaction. Browsers implement a rendering engine and JavaScript runtime capable of processing these technologies. JavaScript applications can use APIs such as Fetch, WebSocket, Web Storage and various device-related interfaces, subject to browser security restrictions. Server-side systems may be implemented in numerous programming languages and frameworks, with the browser generally communicating through HTTP-based interfaces rather than depending on the server's internal implementation language.
Hyperlinks are fundamental to the Web because they connect resources into a navigable information space. A hyperlink contains a reference to another resource, allowing users and software to move from one document or application state to another. Search engines subsequently became a major mechanism for discovering resources that users do not already know how to reach directly. The Web also supports embedded resources such as images, style sheets, scripts, video and fonts, allowing a page to assemble content from multiple locations. Modern pages can therefore involve requests to numerous servers, content delivery networks, APIs and third-party services even when the user perceives the result as one website.
The Web has developed through several broad phases. Early Web pages were predominantly static hypertext documents. Server-side scripting and databases enabled dynamic sites, while JavaScript progressively introduced richer client-side interaction. The term Web 2.0 became associated with highly interactive websites, user-generated content, social platforms and browser-based applications, although it was never a formal technical standard. Modern Web applications increasingly resemble software applications, using client-side state, APIs, background processing, service workers and complex frontend frameworks. Discussions of the Semantic Web have focused on machine-readable relationships and structured data, while later Web architecture has continued to emphasise interoperability, accessibility, decentralisation and standards-based information exchange.
Web security relies on mechanisms including TLS, origin policies, authentication, authorisation, content security controls and secure coding practices. The same-origin policy restricts how scripts from one origin can interact with resources associated with another origin, while Cross-Origin Resource Sharing provides controlled exceptions. Common Web vulnerabilities include cross-site scripting, SQL injection, cross-site request forgery, insecure authentication, access-control failures and server misconfiguration. HTTP cookies are widely used for session management and can be protected with attributes such as Secure, HttpOnly and SameSite. Because websites execute software and process user input, Web security is both a networking issue and an application-development issue.
Accessibility is an important characteristic of a well-designed Web platform. Semantic HTML, appropriate labels, keyboard accessibility, sufficient contrast, alternative text and compatibility with assistive technologies help make web resources usable by people with different abilities. Responsive design allows interfaces to adapt to different screen sizes and input methods. Performance also matters because browser applications depend on network transfer, server processing, rendering and client hardware. Techniques such as caching, compression, content delivery networks, efficient resource loading and appropriate image formats can reduce loading time and bandwidth consumption. These considerations apply independently of the visual complexity of a site.
The World Wide Web is frequently confused with the Internet. The Web is an application and information system that operates over Internet infrastructure, whereas the Internet provides the underlying interconnected networks and protocols through which Web traffic travels. A website is a collection of Web-accessible resources, while a web page is generally an individual document or application view. A browser is client software for accessing Web resources, but the Web is not itself a browser. These distinctions remain important because many Internet services do not use the Web, while Web resources depend on Internet or other IP-based connectivity for ordinary global access.
