The Iowa caucuses are small local meetings where neighbors and strangers stand up to show their support for a particular candidate, and to persuade others to join them.
They're also the first opportunity for Democrats to express their preferences in what’s been a long and tumultuous primary.
Iowa's 41 pledged national delegates are awarded based on the results.
The winner of the caucuses may also get a boost in fundraising, media attention and momentum in the following primaries.
A bad performance could also doom a candidate.
