The door is the gateway to different areas of the compound. Each colored door has a different unique function. To pass a locked door, you must get its corresponding Key (only for some doors). Note that even if an NPC appears to be holding open a locked door, you still cannot get through without a proper key/method of opening it yourself.
There are 12 main types of doors:
Their appearance resembles stereotypical jail doors. They can be freely entered and exited as many times as you want. They are colored white on the map.
Cell (Yellow) Doors
These doors are the entrance of Inmates' cells. They are unlocked during the day, but when the lights out period begins, other cell doors will be locked shut. You will only be able to go through your own cell door, and that will lock when you get inside your cell. They can be opened with the Plastic Cell/Yellow Key.
Entrance (Purple) Doors
These doors are unlocked during the day. However, at night, they deny access to exterior areas, only allowing you to enter the room with your cell. They can be opened with the Plastic Entrance/Purple Key.
Utility (Cyan or Orange) Doors
The utility door, which is orange in PC but cyan in Console, Mobile and all versions of TE2, houses the maintenance crew, ladders, the generator room, and shortcut passageways used by urgent medics. They are locked, but can be opened by getting a Plastic Utility/Cyan/Orange Key.
Staff (Red) Doors
This is a door that secures guard-only areas. They protect the guard quarters, the Control Room, the generator room (sometimes blocked by a utility key), and many escape routes. Opening these requires a Plastic Staff/Red Key.
Work (Green) Doors
This door is the entrance into job rooms. It only unlocks for inmates that occupy the respective job. For example, the kitchen room will only accept chefs, not plumbers. With a Work/Green Key, you can access many employment departments such as the Kennels, the Janitor closet, etc.
Guard (Blue) Doors
These doors are blue on the bottom, with a yellow police star. They are the gate to valuable Contraband Desks. They can only be opened when you are wearing a Guard Outfit or Riot Guard Outfit. On the map they are colored black.
Medic (Dark Green) Doors
These doors are dark green on the bottom, with a green medical cross. They are the gate to medic desks. They can only be opened when you are wearing infirmary overalls/outfit or Medic Outfit (TE2). On the map they are colored black.
Impassable (Grey/Silver) Doors
No matter what you do, this door will not open for you. Only real NPCs can get past. They appear to open in cutscenes, but that is the only time an inmate is shown opening them.
Solitary (Orange) Doors
They look like Free Doors, but they will not open for you unless you have completed your sentence in Solitary. They are orange on the map.
Multiplayer Doors (The Escapists 2)
Main article: Multiplayer Door
They come in two forms: Keycard Doors and Sliding Doors. You need a Keycard of corresponding color to open a keycard door (using a button to allow other players in, who can then use an unlocked inside button to hold the door open). Sliding Doors are opened from the outside by one player holding it open, and the rest can enter and use a button to open the door.