The Internet and its applications

The Internet is the global network of computing and networking devices. Users connect through Internet Service Providers (ISPs), which join into regional and national networks, all linked together.

The World Wide Web (WWW) is different from the Internet: it is a huge collection of interlinked web pages and resources, which runs on the Internet. It was invented by Tim Berners-Lee in 1990, and is built on three technologies:

• HTML (HyperText Markup Language): the language used to design web pages;
• URI/URL: the unique address of each resource;
• HTTP (HyperText Transfer Protocol): the rules for fetching pages. HTTPS is its secure, encrypted version.

Reading a URL: in https://www.example.org/books/maths.html, https is the protocol, www is a subdomain, example.org is the domain name, and the rest is the path to the page.

Other Internet applications:

• Email: sends messages and attachments. cc sends a copy that all recipients can see; bcc (blind carbon copy) sends a copy that others cannot see.
• Chat: real-time text messaging.
• VoIP (Voice over Internet Protocol): voice calls over the Internet; the call quality depends on the Internet speed.