Note: As part of MLB's health and safety protocols during the COVID-19 pandemic, each club will have a 30-man roster for the first two weeks of the 2020 season, 28 for the next two weeks, and 26 for the remainder of the season. Teams will submit 60-man pools -- that is, the group of players who will be able to play for them this season. According to the league's Operating Manual, all players on a 40-man roster "that the club anticipates participating" during the season will be part of the player pool, while the rest will be made up of non-40-man roster players under contract. Each team will be permitted a three-player taxi squad for every road trip, giving them immediate options to replace an injured or COVID-19 infected player. There will be no limit on the number of pitchers on the active roster, or on position players pitching. Rather than a 10-day injured list for position players and 15-day injured list for pitchers, there will be a 10-day injured list for all players in the shortened season. The 60-day injured list will be reduced to 45 days. The 7-day injured list will be unaffected. There will also be a COVID-19 injured list with no minimum or maximum number of days per trip.
In a typical season, the 10-day injured list (known as the 10-day disabled list until the end of the 2018 season) allows clubs to remove injured position players from the 26-man active roster (it was 25, prior to 2020) while keeping them on the 40-man roster. Pitchers and players with the two-way designation (position players who are eligible to pitch in any circumstance) have to stay on the injured list for a minimum of 15 days.
Players can be placed on the 10-day injured list for any type of injury, though players with concussion symptoms are first sent to the 7-day injured list. Players on the 10-day injured list must remain out of action for at least 10 days, though a player can also stay on the list for considerably longer than 10 days, if necessary.
Players may be placed on the 10-day injured list "retroactively," meaning the stint is backdated to the day after the last date on which the player appeared in a game. For instance, if a batter is diagnosed with a bruised hand on June 3 after getting hit by a pitch during a June 1 game, he could be placed on the 10-day injured list on June 3, retroactive to June 2. In that case, he would be eligible to return from the injured list on June 12.
After the 2018 season, the 7-day disabled list (or "DL"), 10-day disabled list and 60-day disabled list were renamed, becoming the 7-day injured list, the 10-day injured list and the 60-day injured list.
As part of the 2017-21 Collective Bargaining Agreement, the 10-day injured list replaced the 15-day injured list as the shortest option for non-concussion injuries. Baseball had a 10-day injured list at various points through its history before it was dropped in 1984.
MLB brought back the 15-day injured list specifically for pitchers and two-way players (position players who are eligible to pitch in any circumstance) prior to the 2020 season.