Democratic debate preview: What to watch for in Night 1

Twenty candidates. Five moderators. Two nights. One stage. The first Democratic presidential debates have arrived.

The action begins at 8 p.m. Wednesday, with 10 candidates stepping under the national spotlight for a two-hour debate in Miami. Twenty-four hours later, 10 more candidates will take their turn.

Debate organizers used a randomized drawing to determine which candidates will appear in which debates. By chance, four of the top five candidates in the polls were placed into the same debate. NBC News opted to conduct that debate on the second night.

To qualify, candidates had to register at least 1 percent support in three polls approved by the Democratic National Committee or collect monetary donations from 65,000 people across 20 states.

• How the debates will work: Each debate will be broken into five segments, according to rules distributed to the campaigns last week. The candidates will have one minute to answer questions and 30 seconds for follow-ups. Everyone will get a 45-second closing statement.

The candidates will be provided water as well as pens and paper. But they will not be allowed to carry notes onstage.

You can watch the debates live on NBC News, MSNBC and Telemundo, which are hosting them. Spanish-language translations will be provided on Telemundo.

Hosts and anchors from the networks will administer the debate and present questions to the candidates. They are Savannah Guthrie, Lester Holt, Chuck Todd, Rachel Maddow and José Díaz-Balart.

• Who's on stage when: Wednesday debate lineup (in alphabetical order): Sen. Cory Booker of New Jersey, former HUD secretary Julián Castro, New York Mayor Bill de Blasio, former Maryland congressman John Delaney, Rep. Tulsi Gabbard of Hawaii, Washington Gov. Jay Inslee, Sen. Amy Klobuchar of Minnesota, former Texas congressman Beto O'Rourke, Rep. Tim Ryan of Ohio and Sen. Elizabeth Warren of Massachusetts.

Thursday debate lineup (in alphabetical order): Sen. Michael Bennet of Colorado, former Vice President Joe Biden, South Bend, Indiana., Mayor Pete Buttigieg, Sen. Kirsten Gillibrand of New York, Sen. Kamala Harris of California, former Colorado governor John Hickenlooper, Sen. Bernie Sanders, I-Vt., Rep. Eric Swalwell of California, author Marianne Williamson and businessman Andrew Yang.