A zero-sum game is a competition among two or more participants for a fixed amount or quantity of winnable goods. Whatever one participant gains necessarily comes at the expense of the other participants. Thus, the sum of all gains (positive) and losses (negative) is zero, hence the name. A situation in which the participants can change the amount or quantity of winnable goods (create or destroy winnable goods) is not a zero-sum game, but is instead a variable-sum game.
Non-economic zero-sum games
Social conservatives recognize that rights are a zero-sum game. As Bill Borst states, "I say that anytime that a new right is born, in the zero sum game of life, it impinges the freedom of another."