The Internet, referring to the specific global system of interconnected IP networks, is a proper noun and written with an initial capital letter. In the media and common use it is often not capitalized, viz. the internet. Some guides specify that the word should be capitalized when used as a noun, but not capitalized when used as a verb or an adjective.^[3] The Internet is also often referred to as the Net.

Historically the word internet was used, uncapitalized, as early as 1883 as a verb and adjective to refer to interconnected motions. Starting in the early 1970s the term internet was used as a shorthand form of the technical term internetwork, the result of interconnecting computer networks with special gateways or routers. It was also used as a verb meaning to connect together, especially for networks.^[4][5]

The terms Internet and World Wide Web are often used interchangeably in everyday speech; it is common to speak of "going on the Internet" when invoking a web browser to view web pages. However, the Internet is a particular global computer network connecting millions of computing devices; the World Wide Web is just one of many services running on the Internet. The Web is a collection of interconnected documents (web pages) and other web resources, linked by hyperlinks and URLs.^[6] In addition to the Web, a multitude of other services are implemented over the Internet, including e-mail, file transfer, remote computer control, newsgroups, and online games. Web (and other) services can be implemented on any intranet, accessible to network users.

Interweb is a mixture of Internet and World Wide Web typically used sarcastically to parody a technically unsavvy user.^[7]