define offset for me

[s13cruzer]

i don't mean exactly what it is but more like , how it works? when ther number gets smaller is the rim gonna be more inward or more outward , i just wanna know because , well .... i don't

thanks

[DSC]

HERE (http://www.tirerack.com/wheels/tech/offset.htm)
They've got a bunch of other good wheel tech info too, browse around.