Who is Ron Paul ?

The First time I ever herd mention of Ron Paul was in an Aaron Russo documentary , video.google.com... ,
In the video , if you don't already know , Ron Paul was briefly interviewed , voicing his opinion on the federal income tax and if there was actually a law that requires Americans to pay it .
Aside from that video and the threads I read here on ATS stating his political views , I know nothing of the man . I know he his a Senator in the States , has he ever held any positions during his time serving as a Senator ? Does he have " friends " in the Senate who share his ideas ? How did he ever come to join the Republican Part ?
I must admit , my lack of info on this man limit the questions I can even ask , but from what I do know of him , I sure would like to learn more .

Dr Paul is not a senator he is a representitive from texas.He joined the republican party because he is a conservetive however his views are always tempered by the constitution so he is more in line with libertarians(IMO)He never in his twenty years in congress has voted for a tax increase.In his twenty years in congress he has never voted against the constitution.Just google ron paul and you'll get lots of hits or you can google campaign for liberty.