In a “zero-sum” situation, it is impossible for one party to advance its position without the other party suffering a corresponding loss. If one side gets $1,000 more, that means the other side gets $1,000 less. The wins and losses add up to zero. These situations typically arise in distributive bargaining cases where a "fixed pie" must be divided between the parties. For example, if two departments are splitting up a fixed amount of money, the more one gets, the less available to the other. Or, if there is only one job, one person will get it and the other person will not. (One job won and one job lost equals zero.)

"Positive-sum" outcomes are those in which the sum of winnings and losses is greater than zero. This becomes possible when the size of the pie is somehow enlarged so that there is more wealth to distribute between the parties than there was originally, or some other way is devised so everyone gets what they want or need.

The most difficult problems are “negative-sum” situations, where the pie is shrinking. In the end, the gains and losses will all add up to less than zero.