The candidates range in age from 37 to 77 years old.
Oldest candidate: Sen. Bernie Sanders, 77 years old
Second oldest candidate: Former Vice President Joe Biden, 76 years old
Youngest candidate: Mayor Pete Buttigieg, 37 years old
Second youngest candidate: Rep. Eric Swalwell, 38 years old
They also differ in terms of experience.
Most political experience: Former VP Joe Biden, 46 years
Neither best-selling author and activist Marianne Williamson nor entrepreneur Andrew Yang have ever held elected office.
Mayor Pete Buttigieg will be the lone candidate on the stage tonight who has served in the United States military.
Some candidates share a common background.
7 candidates attended law school: Biden, Bennet, Buttigieg, Harris, Gillibrand, Swalwell and Yang.
Sen. Sanders, Biden, Gillibrand and Bennet have all served over 10 years in the United States Senate.
Sen. Sanders and Sen. Harris serve together on the U.S. Senate Budget Committee.
Sen. Harris and Sen. Bennet serve together on the U.S. Senate Intelligence Committee.
Sen. Gillibrand and Sen. Bennet serve together on the U.S. Senate Agriculture Committee.
One notable friendship:
Hickenlooper and Bennet have been friends for more than 15 years. They worked together when Hickenlooper served as Denver mayor, and Bennet eventually became the city's superintendent of public schools.
Received two awards from President Barack Obama. In 2015, Yang received the President Ambassador for Global Entrepreneurship, a collaborative initiative tasked to measure entrepreneurial growth. In 2012, Yang received the Champions of Change award. Champions of Change highlighted communities to rise to the challenges of the 21 century.