Each voter may select a single choice to give his total voting power to.
Each voter may select ("approve") any number of choices, each selected choice will receive the full voting power.
Each voter may spread voting power across any number of choices. The results are calculated quadratically, you can test out these calculations here https://wtfisqf.com/
Each voter may rank any number of choices. Votes are initially counted for each voter's top choice. If a candidate has more than half of the vote based on first-choices, that choice wins. If not, then the choice with the fewest votes is eliminated. The voters who selected the defeated choice as a first choice then have their votes added to the totals of their next choice. This process continues until a choice has more than half of the votes. When the field is reduced to two, it has become an "instant runoff" that allows a comparison of the top two choice head-to-head.
Each voter may spread voting power across any number of choices. This voting method was first introduced by Float Protocol with https://scattershot.page (a fork of Snapshot).