When fighting human enemies that use ranged weapons, your survivors can
seek cover to take only
half the ranged damage. Just move your survivor next to a suitable wall and they will take cover automatically.
Survivors in cover are marked by a green shield icon.
When your enemy can see behind the cover, it becomes
exposed and is marked by a red shield icon. Survivors in exposed covers take
full damage from all attacks.
When attacking an enemy, your survivors will automatically seek a cover to shoot from. If you want to avoid this, use the first action point to move to a more suitable place before attacking.