Approval voting is a voting system used for elections, in which each voter can vote for as many or as few candidates as desired. It is typically used for single-winner elections. It can be extended to multiple winners; however, multi-winner approval voting has very different mathematical properties, as noted below. Approval voting is a simple form of range voting, where the range that voters are allowed to express is extremely constrained: accept or not. Approval voting can be compared to Plurality Voting without the rule discarding ballots with overvotes.