A baseball statistic for both infield and outfield players, as well as both starting and relief pitchers, that applies to players who participate in the game at some point or are listed on the starting lineup or as a substitute. It is not necessary for these players to actually take the field nor throw a single pitch for the game to be reflected in G/GP. However, MLB does not allow players who have a G but don't take the field to be eligible for "consecutive games played" consideration.
"Games played" is a bit of a misnomer. In order to be credited with a game, a player simply needs to be listed on the starting lineup card or listed as a substitute, whether or not he takes the field at all. In the case of starting pitchers, some pitchers' stats might reflect 162 games played though it is exceptionally rare for a pitcher to start even 35 games or work once in relief.