Four years ago, the vice presidential debate featured the old Senate pro, Joe Biden, against a newcomer to national politics, Sarah Palin.
Thursday night's debate again includes Biden, now the incumbent Democratic vice president. But this time he's against Republican House Budget Committee Chairman Paul Ryan of Wisconsin.
Palin's folksy style won many conservative fans. Ryan, in contrast, is known for his wonkiness and his proposal to offer future seniors a choice of medical plans.
The constant is Biden, a man prone to gaffes, but possessing encyclopedic knowledge of foreign and domestic affairs.
In a question and answer format, here's what to look for Thursday night.
Q. Who opens and closes?
A. Biden gets the first question. Ryan gets the last word in his closing statement. Viewers won't have to wait long to hear the candidates' answers to debate questions: There are no opening statements.
Q. How long are the debates?
A. Ninety minutes. Each debate begins at 9 p.m. EDT and ends at 10:30 p.m. What if the candidates blow through so many stop signs that 10:30 approaches without covering many planned topics? Too bad. Unless plans are totally upset, airtime ends at 10:30 p.m.
Q. The first of three presidential debates focused on the economy. Will the VP debate have just one topic?
Q. No. There is only one vice presidential debate. While it was tough enough to control the time for only domestic issues in the first presidential debate, this one will have to cover foreign and domestic subjects.
Q. Who will moderate the debate?
A. Martha Raddatz, senior foreign affairs correspondent for ABC News.
Q. How is the time divided?
A. The time will be divided into 10 segments on separate topics. A vigorous debate might preclude the moderator from getting to all of them. Each candidate gets two minutes to respond to a question, followed by a discussion. The two-minute time limits may be generally enforced, but the discussions will keep going until each candidate exhausts the points he wants to make.
Q. Did the Commission on Presidential Debates, which runs the show, make changes as a result of the lengthy discussions in the first debate?
A. No, the commission actually liked the freewheeling debate that often rolled through moderator Jim Lehrer's attempts to move on. Peter Eyre, senior adviser to the commission, said: "The goal is to allow candidates to engage as much as possible. That was exactly what we were looking for when we put the format together."
Q. President Barack Obama and Mitt Romney stood at lecterns. Will Biden and Ryan do the same?
A. No. They will sit at a table shaped like a half moon.
Q. Where is the debate being held?
A. Centre College, Danville, Ky. The commission removed the orchestra pit at the college theater and assembled its own stage from components trucked in from commission headquarters in Washington, D.C.
Q. Who picks the questions?
A. The moderator.
Q. Who runs the commission?
A. The Commission on Presidential Debates was established in 1987. It is a nonprofit, nonpartisan, tax-exempt corporation that has sponsored presidential debates since 1988. The co-chairs are Frank J. Fahrenkopf, Jr., a former Republican National Committee chairman, and Michael McCurry, a former White House press secretary for Bill Clinton.
Q. Is Raddatz the first woman to moderate a vice presidential debate?
A. No. PBS' Gwen Ifill moderated the vice presidential debates in the past in 2004 and 2008.
Commission on Presidential Debates: http://www.debates.org .