Major League Baseball rosters
From Wikipedia, the free encyclopedia
As with nearly all North American professional team sports, the size of Major League Baseball teams is limited by rosters.
There are two different rosters in play for a Major League club: the 25-man roster (also known as the active roster) and the 40-man roster (otherwise known as the expanded roster).
The 25-man roster comprises all the players who may take the field (or "dress") in a game at any given time. Typically, only players on the 25-man roster accompany the club on road trips.
The 40-man roster comprises all of the players on the 25-man roster, plus anyone who is on the 15-day disabled list, and contracted players on "optional assignment" in the minor leagues. A player not on a major-league 40-man roster as of November 20 may be eligible for the Rule 5 draft. From September 1 until the end of the regular season, teams use expanded rosters, so they are allowed to have anybody from the 40-man roster play in games during that final month.