What is Firefox?

Firefox is Mozilla Corporation's popular open source web browser. Firefox was originally intended to be a lightweight version of Mozilla's Netscape (Seamonkey) browser, intended for those who need a web browser only and do not need the rest of the software suite. Since its inception, Firefox has become far more popular than Seamonkey and is considered to be the first browser to seriously challenge Internet Explorer's market dominance. Once marketed as an "alternative" web browser, Firefox is now recommended by standards implementations bodies and by web designers alike for use as a primary web browser.

Although the base Firefox installation is quite sparse, Firefox allows the user to expand its functionality with third-party extensions. These extensions include spell checkers, advertisement blockers, navigation tools, and more. While Mozilla hosts an official extensions website, there are many other sources for Firefox extensions. Note that extensions on Mozilla's website are inspected and therefore considered safer to use than extensions found elsewhere.

Firefox is considered to be much safer to use than Internet Explorer. Also, Firefox lets the user customize the browsers' behavior, thus leaving the user exposed to less "web frustrations" such as popup advertising. Firefox does not use ActiveX controls, so many website exploits will not work on computers running Firefox. However, downloaded files are beyond the browser's control and must be scanned for viruses and other malware, no matter what browser was used to download them.