ram timings

[Unforgiven]

i know a lot about computers and like to help as much as i can on here but i claim complete ignorance when it comes to ram timings/settings. could someone please explain what ram timings are all about and what i should be looking for when making a purchase? im not looking to buy but i would like to more educated when i suggest ram to friends other than just saying "i read somewhere that this is a good choice". i dont get what 3-4-4-8 means and such....any help would be greatly appreciated.

thanks in advance

 

[AtTheGates]

2-3-3-6 = CAS-tRDC-tRP-tRAS
Lower is better with CAS being the most important.
Definitions here

Edit:
Another good article at Tom's

 

[Unforgiven]

awesome man, thank you very very much