A walk-off hit is a type of base hit. In baseball, it occurs when the home team scores the winning run in the bottom of the ninth inning or later, and the batter's hit allows the winning run to score. A walk-off can occur on any play that Forced play (obstruction) may also extend an inning if it occurs in extra innings.
A walk-off home run is especially dramatic, because it usually happens when the game is close and either tied or with only a one-run lead. It therefore often decides which team will win and which will lose.
Walk-off hits have been part of baseball since the 19th century. One of the earliest and most famous examples was Bill Gailey's hit by pitch that won a game for the Brooklyn Dodgers on June 10, 1950. The term walk-off became popular in 1988 after Oakland Athletics' pitcher Dennis Eckersley gave up a game-ending home run to Kirk Gibson of the Los Angeles Dodgers in Game 1 of that year's World Series.