The terms, Internet and World Wide Web, are often used interchangeably in conversation, but they are not the same thing.
Picture if you will, a city. It has stores, art galleries, colleges, arcades, coffee shops, rec centers, billboards, movie theaters, porno shops—more porno shops than you can imagine, libraries, banks, fruit stands, and on and on. It also has traffic signs, directories of local attractions, and some other stuff that you don’t need to worry about much, because you have a skillful and friendly chauffeur. This the Web.
There is, however, much more to the city. There are postal services, telephone systems, radio and television stations, and so on. These are not the Web, and they are not the Internet either. They use the Internet the same way that the Web does.
The Internet is collectively the highways, alleyways, sidewalks, sewers, power lines, and general infrastructure of the city.
Here is a scenario continuing this analogy. Let’s say you want to send an email from your Hotmail address to your friend’s Yahoo address. You use streets (the Internet) to get to your post office (Hotmail website), where you give them a letter for your friend. Their mail truck departs from the back of the post office (email protocol), travels down the street (Internet) to the back of the Yahoo post office where it delivers the letter for your friend (email protocol). The only part of that scenario that involved the Web, was when you walked in the front of the post office, the Hotmail website.
Internet – Wikipedia article
WWW – Wikipedia article
(The graphic at the top was shamelessly ripped from this article without the author’s knowledge or consent.)