Approval ballot

An approval ballot, also called an unordered ballot, is a ballot in which a voter may vote for any number of candidates simultaneously, rather than for just one candidate. Candidates that are selected in a voter's ballot are said to be approved by the voter; the other candidates are said to be disapproved or rejected. Approval ballots do not let the voters specify a preference-order among the candidates they approve; hence the name unordered. This is in contrast to ranked ballots, which are ordered. There are several electoral systems that use approval balloting; they differ in the way in which the election outcome is determined:

• In approval voting, there is a single winner, and he/she is the candidate with the largest number of votes.
• In multiple non-transferable vote (also called block voting) there is a fixed number (say k) of winners, and they are the k candidates with the largest number of votes.
• In other multiwinner approval voting systems, there is a fixed number k of winners, but they are determined by more complex procedures, in order to guarantee such properties as justified representation.

Approval ballots let the voters express dichotomous preferences.