Tomorrow is the Arizona primary.
A Primary is where we go to the voting place where we vote for the least bad person with an R after their name. Or if a Democrat, the least bad person with a D. Libertarians don't necessarily bother since none of the races are generally contested.
Contrast with the general election where we go to the voting place and vote against anyone with a D after their name. (Or R if you are a Democrat) Again, unless you are a Libertarian in which case you actually vote FOR the guy with an L after his name, and then have to decide whether you hate D's or R's more.