The PGA Championship, like all of golf's majors, has a playoff format. It's also distinctly different from the Masters, U.S. Open or British Open.
At the PGA Championship, if two or more golfers are tied after 72 holes, they'll enter a three-hole aggregate playoff, where the lowest total score over the three holes wins. If two or more players are still tied after the three holes, they'll enter a sudden-death playoff for the Wanamaker Trophy. For the 2017 PGA at Quail Hollow Club, the three holes played will be 16, 17 and 18. If still tied, sudden death will start at 18 and go to 16, 17, 18 and repeat as necessary.
The Masters uses a sudden-death playoff, the U.S. Open calls for an 18-hole playoff and the British Open uses a four-hole aggregate. The PGA was last decided by a playoff in 2011, when Keegan Bradley beat Jason Dufner at the Atlanta Athletic Club.