I hear a lot of talk about timing but I never really understood the concept of it. What is might by 'retarding' or 'advancing' the timing by different degrees? How does 'knock' play a role in timing? I don't want to be an expert at this by any means but I would like to know the basics so when people are talking about it I can understand what they are talking about.

 

howstuffworks always has some good basic explanations, with graphics...

http://auto.howstuffworks.com/ignition-system1.htm