For people who live in states with primary elections, the Iowa caucuses can appear to be an ancient ritual requiring a special initiation.

But they can be explained.

Democrats and Republicans hold their caucuses differently, so we will focus on Monday’s Democratic selection process — it’s the one with challengers, while the Republican one is a foregone conclusion.

How it begins

Registered Democrats who will be 18 years old by Election Day meet at 1,678 precinct locations around Iowa, including in people’s homes, public libraries, and schools, starting at 7 p.m. local time (8 p.m. Philadelphia time), and form into groups based on which candidate they support. The neighborhood gatherings last about an hour. There are 99 satellite locations around Iowa, different parts of the country, and overseas for Iowa residents who cannot participate at home, including one at the University of Pennsylvania’s Houston Hall, 3417 Spruce St.

How candidates are chosen

Once voters have formed into groups, a candidate must get support from at least 15% of attendees to achieve viability. If your candidate falls short, you must either support a different viable candidate, join with other nonviable groups to form a viable preference group, or declare yourself uncommitted. Delegates are awarded to the candidates proportionally, based on how many supporters their groups had.

How delegates are awarded

Caucus-goers are essentially choosing 11,402 delegates who will go on March 21 to conventions in Iowa’s 99 counties. Ultimately, after filtering through district conventions on April 25 and the state convention on June 13, Iowa Democrats will send 41 delegates to the party’s national convention, to be held from July 13 to 16 in Milwaukee. The party will also send eight unpledged delegates to the convention.

In a change from past caucuses, the Democrats are releasing three sets of results: “the first expression of preference” before the realignment, the “final expression of preference” after realignment, and, based on the complicated calculation, state delegate equivalents.

Technically, the winner of the most votes statewide after the second alignment can lose in terms of total delegates.

The Iowa Democratic Party doesn’t declare a winner, but historically the person with the most state delegate equivalents has been considered the winner.

Turnout

In 2016, less than 16% of eligible voters — 171,000 — turned out.

But due to the large number of candidates this year, the Iowa Democratic Party is expecting to break the record turnout of 239,000 voters set in 2008.