Meet the Republican candidates
Mitt Romney is the Republican candidate for president. He was the governor of Massachusetts from 2003 to 2007.
Romney was born in Detroit in 1947. He is 65 years old. He went to Brigham Young University and Harvard University. He and his wife, Ann, have five grown sons.
He has worked in the business world and was the leader of the 2002 Salt Lake City Olympic Games Organizing Committee.
Paul Ryan is the Republican candidate for vice president. He is a member of the U.S. House of Representatives from Wisconsin.
Ryan was born in 1970 in Janesville, Wis. He is 42 years old. He studied at Miami University in Ohio. His family includes his wife, Janna, and three children.
Before he was elected to Congress, Ryan worked for Wisconsin Sen. Bob Kasten.
Meet the Democratic candidates
President Obama is the Democratic candidate for president. He is called an incumbent because he is running for his second term as president.
Obama was born in Hawaii in 1961. He is 51 years old. He studied at Occidental College, Columbia University and Harvard Law School. Obama and his wife, Michelle, are the parents of two young daughters.
Before he was president, Obama was a U.S. senator from Illinois and a state senator. He has also worked as a lawyer and a professor.
Vice President Biden is the Democratic candidate for vice president. He is also an incumbent.
Biden was born in Scranton, Pa., in 1942. He is 70 years old. He graduated from the University of Delaware and Syracuse University. Biden and his wife, Jill, have three grown children.
Biden was a U.S. senator from Delaware from 1973 until he became vice president in 2008. Before that, he was a lawyer.