These Smashing people provide real concise info.
Note their quite though:
Disclaimer: the things we’ll talk about in this article today won’t make you a security expert, just as buying a Swiss Army knife won’t make you a locksmith or buying a whip won’t make you a lion tamer. The purpose here is to raise awareness and perhaps make some of that security mumbo-jumbo a bit more understandable to you.
Web Security: Are You Part Of The Problem? – Smashing Magazine.