Where is the legitimate “free credit report” website?

trang asked:

You hear from all sorts of places about getting your free credit report, but you just have to sign up for a free trial. And there’s always that catch. I saw something yesterday on the TV about a free credit report being offered and the offer expires end this month? I can’t remember who it was.

Also, that offer aside, what is the legit place to get access to your once a year, free credit report? I don’t trust half of what I read….