This helpful Google article explains what Google Docs are and how to use them: http://support.google.com/docs/bin/answer.py?hl=en&answer=49008. The first paragraph of the article is shown below.
"What is Google Docs?
Google Docs is a suite of products that lets you create different kinds of online documents, work on them in real time with other people, and store your documents and your other files -- all online, and all for free. With an Internet connection, you can access your documents and files from any computer, anywhere in the world. (There's even some work you can do without an Internet connection!) This guide will give you a quick overview of the many things that you can do in Google Docs."