Prior to the 2019 season, the "Injured List" was known as the "Disabled List."  

There are four different types of MLB injured lists: the 7-day Injured List (for players suffering an acute concussion), the 10-day Injured List (for position-players only), the 15-day Injured List (for pitchers and for "two-way players"), and the 60-day Injured List (AKA the "Emergency Injured List").
CoViD-19 EXCEPTION: There is a special MLB "CoViD-19 Related Injured List" in 2022 for players who are diagnosed with CoViD-19 during the MLB regular season, as well as for players who exhibit symptoms and/or have been exposed to the virus, or who are in a CoViD-19 "high risk" group. A player can only be placed on the CiViD-19 Related Injured List by consent of the CoViD-19 Joint Health & Safety Committee. There is no minimum or maximum number of days a player must spend on this list, but a player may not be reinstated until he is symptom-free and tests negative for the virus twice where the tests are administered at least 24 hours apart. A player on the CoViD-19 Injured List does not count against his club's Reserve List or Active List.     
NOTE: The 15-day IL for pitchers and two-way players will be a 10-day IL through May 1, 2022. 

PLAYERS ON CUBS MLB 60-DAY IL (updated 5-15-2023) 
Codi Heuer, RHP (2/20)
Ethan Roberts, RHP (2/17)
Adrian Sampson, RHP (5/4)

There are only two types of minor league injured lists: the 7-day Injured List and the 60-day Injured List.

Only players with a verified injury or illness may be placed on an injured list.

The MLB Commissioner (or the Commissioner's designate) must approve all MLB Injured List assignments.

A "Standard Form of Diagnosis" signed by the club physician must accompany a request to place a player on an MLB or minor league injured list, and a "Standard Form of Diagnosis for Recertification" signed by the club physician must be filed with the MLB Commissioner after seven days for a player on an MLB 7-day (concussion) IL, every 15 days for a player on an MLB 15-day IL, every ten days for a player on an MLB 10-day IL, and every seven days for a player on a minor league 7-day IL. If a "Standard Form of Diagnosis for Recertification" is not submitted by the deadline, the player must be either reinstated from the IL or transferred to the 60-day IL.  
NOTE: A Standard Form of Diagnosis for Recertification is NOT required once a player has been placed on or transferred to an MLB or minor league 60-day IL. 

A "Return to Play" form signed by the club's physician must be submitted to the MLB Commissioner before a player can be reinstated from the MLB 7-day (acute concussion) Injured List.

There is no limit to the number of players who may be on a club's injured list(s) at any one time.

1. An ill or injured player who is placed on the MLB 7-day, 10-day, or 15-day IL or on the minor league 7-day IL does not count against his club's Active List, but he does count against his club's Reserve List.

2. A player cannot be placed on the MLB 7-day, 10-day, or 15-day IL after the conclusion of the MLB regular season and throughout the post-season, off-season, and Spring Training, and a minor league player can be placed on a minor league club's 7-day IL only during his minor league club's regular season.
EXCEPTION: With consent of the MLB Commissioner, a player on an MLB Active List (26-man roster) of a club that is active in the MLB post-season can be placed on the 7-day, 10-day, or 15 day Injured List during a post-season series.  

3. As long as the player did not appear in a game during the retroactive period (including "official" MLB Cactus League or Grapefruit League games or other MLB pre-season exhibition games), an MLB 10-day or 15-day Injured List assignment can be backdated up to three days (including the three days prior to MLB Opening Day), and a 7-day (acute concussion) Injured List assignment can be backdated up to four days (including the four days prior to MLB Opening Day).

4. If a position-player on an MLB 7-day (acute concussion) Injured List is not reinstated after spending nine days on the list he is automatically transferred to his club's 10-day Injured List, and if a pitcher on an MLB 7-day (acute concussion) Injured List is not reinstated after spending at least 14 days on the list he is automatically transferred to his club's 15-day Injured List. 
CoViD-19 EXCEPTION: The MLB 15 day Injured List (for pitchers and two-way players) has been suspended in 2021 (here will be a 10-day Injured List for position players, pitchers, and two-way players).    

5. During Spring Training and during the MLB regular season up through August 31st, an injured or ill player can be placed on or transferred to the MLB 60-day Injured List only if his club's reserve list is full, but if a player is placed on or transferred to the MLB 60-day Injured List after August 31st, the club's reserve list must be full - AND - the player must be replaced on his club's MLB Reserve List (40-man roster) by another player.

6. A player on the 60-day Injured List does not count against his club's Reserve List ir Active List roster limit. 
CoViD-19 EXCEPTION: A player on the CoViD-19 Related Injured List does not count against his club's Reserve List, Active List roster, or Club Player Pool limits.   

7. A player can be transferred from the MLB 7-day, 10-day, or 15-day Injured List to the MLB 60-day Injured List (or minor league 7-day Injured List to minor league 60-day Injured List). However, a player cannot be moved back to the MLB 7-day, 10-day, or 15-day Injured List and a minor league player cannot be moved back to the 7-day Injured List once he is placed on or transferred to the 60-day Injured List.

8. A player cannot be placed on the MLB 60-day IL after the conclusion of the MLB regular season, and during the post-season and off-season, up until the start of Spring Training (beginning on the date that pitchers & catchers are scheduled to report). A minor league player can be placed on a minor league club's 60-day Injured List only during his minor league club's regular season.

9. For a player who is transferred from the MLB 7-day, 10-day, ot 15-day Injured List to the MLB 60-day Injured List (or from a minor league club's 7-day Injured List to the minor league club's 60-day Injured List), time spent on the MLB 7-day, 10-day, or 15-day Injured List (or minor league 7-day Injured List) during the MLB regular season (or during the minor league regular season) prior to being transferred counts toward the minimum 60 days a player must spend on the 60-day Injured List. However, time spent on a minor league 7-day Injured List or minor league 60-day Injured List does NOT count toward the minimum number of days a player must spend on an MLB Injured List if a player is recalled from an optional assignment or has his contract selected and is added to an MLB 40-man roster prior to being reinstated from a minor league injured list.

10. A player who is placed on the MLB 60-day Injured List during Spring Training must spend at least the first 60 days of the MLB regular season on the Injured List (the player cannot be reinstated any earlier than the 61st day of the MLB regular season).

11. A player who was placed on the an MLB 7-day, 10-day, or 15-day Injured List during the MLB regular season must be reinstated no later than the day after the conclusion of the club's MLB season  (including the post-season for clubs that qualify for the post-season), a player on an MLB 60-day Injured List who is eligible to be an Article XX-B MLB free-agent must be reinstated from the Injured List no later than 9 AM (Eastern) on the day after the final game of the World Series (or no later than 9 AM Eastern on October 15th if the World Series is cancelled), and all other players on an MLB 60-day Injured List must be reinstated no later than 5 PM (Eastern) on the 5th day after the final game of the World Series (or no later than 5 PM Eastern on October 15th if the World Series is cancelled), even if the player did not spend at least 60 days on the 60-day IL.
CoViD-19 EXCEPTION:  A player on the MLB CoViD-19 Related Injured List who is eligible to be an Article XX-B MLB free-agent must be reinstated no later than 9 AM (Eastern) on the day after the final game of the World Series (or no later than 9 AM Eastern on October 15th if the World Series is cancelled), and all other players on an MLB CoViD-19 Injured List must be reinstated no later than 5 PM (Eastern) on the 5th day after the final game of the World Series (or no later than 5 PM Eastern on October 15th if the World Series is cancelled),

12. A minor league player cannot be placed onto or transferred to a minor league 60-day Injured List until the player has spent at least five days on the club's Domestic Reserve List. 

13. A player on a minor league club's 60-day IL must be reinstated no later than 5 PM (Eastern) on the 5th day after the conclusion of the World Series, even if the player did not spend 60 days on the Injured List. 

A player on an injured list can be traded, even if the player is not eligible to be reinstated and/or healthy enough to play. 

If a player on an injured list is traded, the player can be transferred directly from his former club's 7-day, 10-day, 15-day, or 60-day Injured List to the corresponding Injured List of his new club. Time spent on a 7-day, 10-day, 15-day, or 60-day Injured List prior to the trade counts toward the minimum number of days required before the player is eligible to be reinstated.

If a player on an MLB 60-day Injured List or CoViD-19 Injured List is claimed off waivers after the conclusion of the MLB regular season but prior to the deadline for reinstating players from the 60-day or CoViD-19 injured lists, the player can be transferred directly to the 60-day Injured List or CoViD-19 Injured List of his new club.

A player accrues one day of MLB Service Time for each day of the MLB regular season spent on an MLB Injured List.