What is good and bad timing for RAM? How do you tell and what does the #'s mean?

[ADE]

What sequence of numbers means good timing and are bigger numbers better or worse? And is 2-3-2-5 good or bad?

 

[Emperor_nero]

The lower the timing the better and I think that 2-3-2-5 is pretty good, I'm not sure about the last part though.