STAR stands for Score Then Automatic Runoff:

Give your favorite 5 stars, give your least favorite zero and score the others as you like.
You can vote your conscience.
You don't have to worry about voting for the lesser of two evils or wasting your vote.

Ballots are tallied by adding all the scores for each candidate:

The two highest scoring candidates are finalists who advance to an automatic runoff.
The remaining candidates are out of the running.
In the runoff, each ballot counts as one vote for the finalist that voter preferred. 

The finalist with the most votes wins. 

Why STAR Voting?

STAR Voting is non-partisan.

We should be able to vote our conscience, our votes should never be wasted, and our elections should accurately reflect the will of the people.

The initiative would establish STAR voting, where voters rate the candidates for a given office and the top two finishers advance to an automatic runoff.