The Cover system is a system to let the player take cover from gun fire is a feature that has debuted with the introduction of over-the-shoulder view in Grand Theft Auto III and has been immensely expanded in Grand Theft Auto IV. Games that uses the bird's eye view have very little form of cover, mainly only running behind objects to hide from gun fire.
In Grand Theft Auto III, in order to cover from gunfire, the player is limited to running behind cars and structures, or hiding behind objects. With the introduction of crouching in Grand Theft Auto: Vice City, the player can run behind shorter structures that are otherwise pointless in GTA III so the player's body is less exposed to gunfire. This is especially advantageous on the PC version where the bullets travel to the crosshair and not obstructed by barriers usually experienced using the console or classic controls. Powerful weapons that can only be targeted in first-person view in the console or classic controls are extremely useful in the PC version being able to target in third person view. Grand Theft Auto: San Andreas added the additional ability to move and roll sideways while crouching. In Grand Theft Auto: Liberty City Stories there was a feature to crouch but it was cut. Cops also take cover in all 3D Universe games, even GTA III, because there is an animation which only 8-Ball (in the mission Bomb Da Base: Act II, to hide from the cartel while planting the bomb) and the cops, SWAT, FBI and Army use.
Grand Theft Auto IV dramatically expanded this idea into a system with a simple press of a button. The cover button can let the player automatically find a nearby object to hide behind. A great number of animations are available just to approach the cover, including running into cover, rolling into cover, sliding into cover, and going from cover to cover.
Once behind cover, the player can strafe left or right if there is room, hugging close to the cover. At the edge of a cover, the player can blind fire without exposing the major parts of the body to receive minimal damage. A major disadvantage to this is that accuracy is dramatically reduced. The new system allows the player to throw projectiles and explosives without damaging oneself in the process. The player can shoot out of cover instead and after the player stops shooting, the character will automatically hide behind cover.
Grand Theft Auto V utilizes similar cover mechanics to those in GTA IV. With the press of a button, the player will automatically find the nearest solid object to take cover behind. The player can also blind fire around corners although he exposes himself to gunfire, yet less so than when aiming, and at the cost of reduced shooting accuracy. In contrast to GTA IV, GTA V's cover animation is much smoother, with Michael, Trevor, or Franklin being able to get behind cover quickly and smoothly.
A big change in the new cover system is that a reticle isn't displayed while in cover even when blind-firing, but only when the player is shooting while aiming. However, the player can push the left thumbstick in the according direction to make the character peek out (e.g. push up to look over a car the player his hiding behind), which will display the reticle again. This way the player can aim the reticle while exposing himself only minimally to gunfire, and he will be shooting at that spot when blind-firing.