The Internet, the World Wide Web, and HTTP

The internet is the hardware layer: millions of computers, routers, and cables wired together so any device can send packets to any other. It does not care what the data means. The World Wide Web is one application built on top of that network: a huge set of documents, identified by addresses, that link to each other and get requested with the Hypertext Transfer Protocol, or HTTP. People say internet when they mean web because the web is the part they see, but the internet existed before the web and carries plenty of traffic that is not web traffic.

HTTP is the agreement that lets a browser ask a server for a document and get it back in a form the browser can render. Press enter on a web address, and the browser first finds the server's address, opens a connection, and sends an HTTP request. The server sends back the page's code, broken into packets that travel independently across the internet, possibly by different paths, and get reassembled on arrival. The browser reads that code and draws the page, then fires off more requests for images, style files, and scripts the page links to, which is why one page view often means many HTTP requests.

Email is not part of the web because it never uses HTTP to move mail between servers; it uses its own protocols, like SMTP, built separately on the same underlying internet. This is the key distinction: the internet is shared infrastructure, and the web, email, and other services are separate systems that each define their own rules for using it. Everything the web does, in turn, depends entirely on packets being routed and delivered correctly underneath, which is the job of the internet itself.