World Wide Web

The World Wide Web (WWW), commonly called the web, is a global information system of documents and applications identified by URLs, linked by hyperlinks and delivered over the internet using the HTTP protocol. It is one service that runs on top of the internet, not the internet itself: the internet is the network of networks that moves packets, while the web is the application layer of linked resources that browsers request and display.

Among internet fundamentals, the web is the most visible application. It was proposed at CERN in 1989 by Tim Berners-Lee, opened to the public in the early 1990s and released for royalty-free use in 1993, a decision that allowed it to grow into the dominant platform for publishing, commerce and software delivery.

How the World Wide Web works

The web rests on three original building blocks that still define it. A URL names every resource and says where and how to obtain it. HTTP is the request and response protocol that transfers resources between clients and servers. HTML describes documents and, crucially, the hyperlinks that connect them into a web.

A typical page view follows a fixed chain. The browser resolves the domain name through DNS, opens a connection secured by TLS, sends an HTTP request, receives HTML and then fetches the stylesheets, scripts, images and fonts referenced inside it. A modern page often requires dozens of such requests to different servers.

The web follows a client and server model. Web servers publish resources and answer requests; clients, usually browsers but also search engine crawlers, mobile apps and scripts, consume them. Because the protocol is open and text-based in its semantics, any program that speaks HTTP can take part, which is why the same infrastructure now serves human-readable pages and machine-readable web APIs exchanging JSON between applications.

The web compared with the internet

The words web and internet are often used interchangeably, but they name different layers. The internet carries the web, and it also carries many services that have nothing to do with web browsing.

The distinction matters in practice. An internet outage breaks the web, but a web server failure leaves email, DNS and other services untouched. Likewise, the deep web refers to web content not indexed by search engines, which is still part of the web rather than a separate network.

Evolution of the web

The web has changed from static hypertext documents to a full application platform. Its core architecture stayed stable while capabilities were layered on top.

The marketing labels Web 2.0 and Web3 describe business and social trends rather than formal technical versions; the web has no numbered releases, only continuously updated standards such as the HTML Living Standard.

Principles that shaped the web

Several design principles explain why the web scaled to billions of users. Decentralization means anyone can publish a server without permission from a central authority. Universal addressing through URLs allows any resource to link to any other. Royalty-free standards let any company build browsers and servers without license fees.

The web is also intentionally stateless at the protocol level: each HTTP request stands alone, and state is added through cookies, tokens and storage. Combined with caching and content delivery networks, this design lets popular resources be served from servers close to users, which is a major reason the web scales efficiently.

• Backward compatibility: browsers still render pages written decades ago.
• Progressive enhancement: basic content works even when advanced features are missing.
• Open standards process: specifications are developed in public working groups.

Limitations and persistent challenges

Hyperlinks on the web are one-directional and can break. When a page moves or disappears, links to it fail, a phenomenon known as link rot that makes long-term references fragile. Archiving efforts preserve snapshots, but no mechanism guarantees permanence.

Other challenges are structural: concentration of traffic on a few large platforms despite a decentralized design, tracking and privacy concerns built around cookies and scripts, uneven accessibility for people using assistive technology, and growing page weight that penalizes users on slow connections. Many current web standards, such as HTTPS everywhere and accessibility guidelines, exist specifically to address these weaknesses.

In plain words

Think of the internet as a road network connecting every city in the world. The World Wide Web is one kind of traffic on those roads: a vast library of pages that point to one another, which anyone can read with a browser.

Each page has an address, much like a street address, and clicking a link takes you straight to another address anywhere in the world. Email and video calls use the same roads but are not part of this library. The web is the part of the internet you visit with a browser.

A real-world example

A small bakery wants customers to find its opening hours and order cakes online. It registers a domain name, rents hosting, and publishes a few HTML pages with a menu, a contact page and an order form. Customers type the address or follow a link from a search result, and their browsers request each page over HTTPS.

The bakery’s email, card terminal and phone system also use the internet, but only the website is part of the web. When the hosting server has a short outage one morning, customers cannot open the site, yet incoming order emails keep arriving. The owner thus sees in practice that the web is one service running on the internet, not the network itself.