how to edit a pdf file in linux

["J.S.Sahambi" <jsahambi@iitg.ernet.in>]

I just now saw that in windows the pdf files can be edited very nicely 
and it can be used to add comments for revision. I found this feature 
very interesting and useful for adding comments while reviewing research 
papers. I would like to know can this be done in Linux?

(Frankly speaking I dont want to boot windows for just adding comments 
to a pdf file ;) )

Any help will be appreciated.

JSS