In baseball, a walk-off home run is a home run that ends the game. It must be a home run that gives the home team the lead in the bottom of the 9th inning or the bottom of any extra inning. It is called a "walk-off" home run because the teams walk off the field immediately afterward. Sportscasters will also use the term "walk-off double" or other such terms if such a hit drives in the winning run to end the game. Although the concept is as old as baseball, the term itself has come into use only in the last several decades.