There are three the most important factors at chess that every player needs to take into account. These are material, space and time. Most chess players know what the material is: pieces and pawns. Each of the pieces has a relative pawn value that can be assigned to it. For example, a minor piece is equal to 3 pawns, while a pawn is equal to roughly 3 tempos. That means if you sacrifice a pawn without any material gain, you better get at least three tempos ahead.