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Parity in sports is defined as attempting to make an equal playing field for all participants, specifically with regard to financial issues. When parity in a sports league is achieved, all participating teams enjoy roughly equivalent levels of talent. In such a league, the "best" team is not significantly better than the "worst" team. This leads to more competitive contests where the winner cannot be easily predicted in advance. Such games are more entertaining and captivating for the spectators. The opposite condition, which could be considered "disparity" between teams, is a condition where the elite teams are so much more talented that the lesser teams are hopelessly outmatched.

Different major governing organizations attempt to achieve parity in different ways. For example, the NFL in America has established the shared revenue plan, in which all teams equally benefit from television revenue and sales of NFL franchised goods.

Many consider the NFL to be the most "fair" or competitive league, with many different teams having a chance to win each year. In the NFL, complete parity would be a state where on any given Sunday, any given team can win any given game.

An example of disparity would be Portuguese Liga, the top-flight professional football (soccer) league in Portugal, where three clubs have accounted for 71 of the 73 championships in league history.

Salary cap limits set a maximum amount of money that may be spent on athletes' contracts. These limits exist to different extents in several other leagues as well. For example, Major League Baseball in America has cap limits, but allows for teams to go over the limit if they are willing to pay a luxury tax.