The Counterfeit Coin

Problem

You have 8 coins that are identical in appearance. Seven of them have the same weight, but one coin is counterfeit and weighs slightly less than the others. You cannot tell the difference by looking at or feeling the coins.

You have a balance scale that compares the weight of whatever is placed on its two pans. The scale tells you which side is heavier, or if both sides are equal. You are allowed exactly 2 weighings.

Describe a strategy that guarantees you will identify the counterfeit (lighter) coin in at most 2 uses of the balance scale.