Garlic is an important character in the pasta scenario, although not by any means an essential one. It is used a lot, but not in every sauce, and when used it is used with discretion.
It is always peeled before use; it may then be added either lightly crushed but whole and then removed, or chopped and left in the sauce. The thinner the garlic is cut, the stronger it tastes. When sautéing, garlic should not be allowed to become brown, or it will taste bitter.
When I use garlic that is no longer fresh, I cut the clove in half and remove the green germ, or shoot, which is the more pungent part of the garlic.