The internet, Internet, interwebs, or internets is a global network of millions of smaller computer networks. It is not to be confused with the "World Wide Web" that gives us the www subdomain, any series of tubes you might come upon, or real life.
"Internet" vs. "World Wide Web"
What most people call the "Internet" is actually the World Wide Web, as the general public will use the terms interchangeably.
The Internet actually began in 1969, and has roots much, much older than that. The de facto creation occurred in October 1969, (with what was called the ARPANET) when "e-mail" messages were first exchanged by two university computers: one at Stanford University, and the other at U.C.L.A. Through a series of various developments and incarnations in the 70's, this later gave way to TCP/IP by 1982, whose final form of which is what we see as today's internet.
By contrast, the World Wide Web, which was launched in 1991, is a
series of tubes collection of hypertext documents and domains that use the internet via web servers. Even then, it took until the late 90s for this to become anything like today's internet, as computer speeds have increased exponentially since then. No one imagines that the internet existed before the 90s, but it was very much around. This misconception is because it was only used mainly by the government, the military, and university personnel, and the fact that most people would not be able to house or afford computers the size of buildings, which would be required.