Can someone quickly explain to me exactly whats up with these "droid" phones?

im really good with technology and whats going on, so dont bother trying to explain it SUPER simply. But i have had my iphone since 2007 and up until now the competition was few. But im hearing about these droid phones constantly and have looked them up online and some of them really seem to outshine the iphone. even the 4! my question is…i know “Android 2.1” is the latest version of GOOGLE’s mobile OS, but is “droid” short for android? or is droid a type of phone that RUNS android? im seeing all these other phones now…HTC, EVO, Xtreme, Incredible, etc. are these droid phones? or do these phones rund android but are made by all different companies. Then I’m hearing about phones running android, AND other OS’s at the same time? HTC apparently has an OS that runs WITH android? am i crazy or is this all correct? Thanks! Also, which “Droid/HTC phone is the BEST at the moment? Incredible? Evo? Xtreme (coming later this month)?