First preference

A first preference or 1st choice is a voter's highest preference for who they want to win i.e. if the voter had complete power to decide who won, this is the candidate they would pick.

Multi-winner case
Instead of looking only at 1st choices, it is useful to instead look at each voter's [number of winners] most-preferred candidates, because these are the candidates they would choose to fill all of the seats if they could. See solid coalition.