Responsive CSS Frameworks: What to use?!

The 960 Grid systems are the way to develop a faster websites. At the mean time, developing websites should support mobile browsers while mobile usage is increasing. So, supporting all screen sizes called: Responsive web.

I am not writing this to talk about this, i am writing it to give me details and features about several Grid Systems that mostly common. This will help you decide, what to use? and what is suitable for you.