What doents am I looking for in a Title search?

I am told I should do a title search at the county office for every likely property I think I want to start negotiations on. I have one in pre foreclosure, and another that is bank owned. What doents should I be looking for? Is there are easier way such as an online search? Will the real estate broker do this for me? It's not that I don't want to learn how to do it, it's just that I would be nervous I might miss something important.