This is the card or piece of paper which contains the entire lineup from both teams for a single game. In Major League Baseball, each card contains for both teams: the batting order with the players last name and sometimes their number, as well as their position, the position players available and the pitchers available, both categorized by handedness. Lineup cards have been a part of baseball from the beginning of the modern game, though they were not always quite as formal. The traditional use of the lineup card was to list the batting order in the dugout.
Lineup cards have become very valuable items when they come from important games. Many historical lineup cards have fetched big sums of money. The most valuable cards come from World Series games. Outside of their appeal to collectors, lineup cards are only used to convey to the umpiring crew the batting order and who the available players are. After the game, the cards are turned in for official record keeping.