ignition timing

just what is ignition timing.....what are the degrees and everything else they are talking about...

thanks in advance

Ignition timing is measured in degrees. If I say 10 degrees before TDC, that means the ignition fires 10 degrees (crankshaft revolutions) before [top dead center (the point in the cylinder where the piston has reached it's peak)]. If your timing is before TDC, it's advanced, if it's after TDC it's retarded and if it is at 0 degrees then its "straight up".