Leadoff hitter

In baseball, a leadoff hitter is a batter who bats first in the lineup. It can also refer to any batter who bats first in an inning.

Leadoff hitters must possess certain traits to be successful: they must reach base at a proficient on-base percentage rate and be able to steal bases. Sabermetric analysis has indicated that the ability to steal bases is often an overrated quality of leadoff hitters; however, the leadoff hitter should still take a large lead at first and draw a throw from the pitcher. This is useful because it shows the team the pitcher's pick-off move. Many managers also wish their leadoff hitters to take a lot of pitches, to work high pitch counts, to give their teammates a feel for the opposing pitcher, as well as raising his pitch count. Another job, often unknown and unappreciated, is also the responsibility of the leadoff hitter. In the National League, after the pitcher bats (he usually drops a sacrifice bunt), the next hitter is usually the first man in the lineup. His responsibility is to take his time walking to the plate so the pitcher doesn't have to run back to the dugout, which would waste energy and risk unwanted injury. Also, because the leadoff hitter is first in the lineup cycle of batters, he will usually be the player who at least ties for most plate appearances per game on his team.

Leadoff hitters tend to play defensively difficult positions, such as shortstop, second base, and center field. Rickey Henderson is widely regarded as the prototypical leadoff hitter.

...
Wikipedia