It seems Mozilla is busy developing Firefox and incorporating some new and cool features. After the release of its various versions, Firefox 3.5 RC3 is also available for download now.
RC stands for Release Candidate and it would interest you to know that Mozilla has released RC3 build of Firefox 3.5. It is recommended that if you are currently using the Firefox 3.5 beta or RC, you should upgrade to the RC3 one which would provide better browsing for sure.
Firefox recently released Firefox 3.5 Beta, then it was Firefox 3.5 RC 1 and then Firefox 3.5 RC 2 but finally it has released the RC3 build for the users.