Turrets come in many forms.
Turrets are built by techs and require parts to construct. They can be compacted and sold to other classes, however the only other class that can unpack and deploy them is the Mercenary Soldier.
Types
Stationary: Stationary turrets only fire in one direction.
Rotating: Rotating turrets can fire in all directions, and every few pulses they check the rooms around them.
Roving: Roving turrets actually move around, though the movement is random, they act similar to rotating turrets.
Classifications
Machine Turret: Fires 2-5 rounds into an enemy.
Fire Turret: Fires a steady stream of flame.
Gas Turret: Fires out canisters of noxious gas that damages everyone in room.
Concussive Turret: Fires out rounds that damage everyone in the room.
*Turrets will only fire as long as they have the correct ammunition loaded/in inventory. They are usually created with a few rounds already, but usually not that many.