Firefox is a web browser, examples of which youíve certainly seen Ė youíre using one right now. Itís probably Internet Explorer, AOL, Netscape, or Safari, but theyíre all basically the same thing. They render html code so that it looks all pretty, like the document youíre viewing now.
The distinctions Firefox has that cause me to use it are as follows: itís completely free, and itís incredibly customizable. As you can see in the picture below this paragraph, I have myself added a search bar for dictionary.com, along with many other websites like Amazon.com, Wikipedia, and Ebay, as well as a different skin and the all-to-useful Google search bar.
The geek news website Slashdot, as rendered by Firefox.