Such answers are not all helpful...
You are right sanjay. Even I believe that the way how anisha answered your question was not correct. Most of the people who started using linux will become an expert google-searcher in few days, otherwise he/she cannot survive with linux. So simply saying like "put these words in google" will never serve the purpose. By the way, those key words given by anisha did not serve any purpose for the question. The blog which appears at the top as a result of searching says nothing about a linux tool for pdf annotation or highlighting. Please at least carefully read a blog when you open that. At least you can study something from that. PDF-Xchange viewer is a windows based tool, and buddy you need wine to run that. If someone really likes native linux tools, and those who really dislike the killing sluggishness of wine's behaviour would never ever choose such a tool. I dont understand, why people cant just keep quiet if they know nothing. And to sanjay, Even I am in a search of a decent tool. Till this time I could not find it. The only one which I found was Xournal. That is ok but not really good.