Preferential Voting

Preferential voting (or preference voting) is a type of ballot structure used in several electoral systems in which voters rank a list or group of candidates in order of preference. For example, the voter may write a '1' beside their first choice, a '2' beside their second preference, and so on. This contrasts with ballots used by methods which do not allow more than two-valued ranking of candidates (Yes or No, often with No assumed unless Yes is marked). The Fuzzy preferential ballot will require voters to write in order of preference their three favourite names.

A more detailed description of preferential voting is available on Wikipedia.