How will it work?
The debates begin at 9 p.m. EDT and run for two hours at the Adrienne Arsht Center for the Performing Arts of Miami-Dade County.
They will be shown live on NBC, MSNBC, and Telemundo.
The hosts are Savannah Guthrie, Lester Holt, and Chuck Todd of NBC News, with Rachel Maddow of MSNBC and José Diaz-Balart of Telemundo.
The candidates will be arranged with the front-runners in the center and those ranked lower in the polls standing towards the outside.
Just 120 minutes is not much time for 10 candidates, so expect plenty of sharp elbows as the runners compete for the spotlight.
Who is appearing on Thursday?
The Democratic National Committee wanted to avoid repeating the Republican method of 2016, when a large field was divided into a main field and an undercard or "kiddy table." Instead, they divided the runners into those polling above 2% and those below and made up each night's slate with a random mix from each of those pots.
However, that did not prevent Thursday night becoming something of the main draw, with four of the top five ranked candidates in the polls: Joe Biden, the former vice president, Bernie Sanders, the Vermont senator, Kamala Harris, of California, and Pete Buttigieg, mayor of South Bend, Indiana.
Marianne Williamson, author and activist, John Hickenlooper, former governor of Colorado, Andrew Yang, an entrepreneur, Kirsten Gillibrand, New York senator, Michael Bennet, Colorado senator, and Eric Swalwell, California representative, make up the rest of the field.