Every four years, Iowans on both sides of the political aisle gather for hours in living rooms, church basements, and now even sites around the world to cast the nation’s first votes on nominees in the presidential election. The Iowa caucus—scheduled this year for Monday, February 3—is both the kickoff to the presidential nomination process and a time-honored political tradition. But it has lost ground in recent years to its more popular alternative: the political primary. But what is the difference between them?

First things first: Caucuses are not primaries. During a presidential caucus, state political party supporters gather to elect delegates to represent them at a state presidential nominating convention. These in-person gatherings can last for hours and