While there is some debate about whether it's important to win the Iowa caucus (George W. Bush and Barack Obama won both times they ran, but Bill Clinton lost his first time running to Tom Harkin, who had 76 percent of the vote), it is an important process that kicks off the primary season. But it's not a primary—the first one of those is New Hampshire. So what is a caucus and how does it work? Surprisingly, it's more complicated than a simple ballot vote.
Check out this fun video from Vox that explains the process in more detail (with excellent elevator music for your listening pleasure):