Shotguns have the highest close-range accuracy of all guns, although their accurate range is severely limited. They usually fire pellet munitions which have huge damage potential, but are completely useless against armored targets.
Shotguns don't require high abilities to use (the base skill is 50 + Firing/2).
Shotguns are best used in close quarters combat, where they almost guarantee a one-shot-kill against ordinary enemies; their CQ accuracy is similar to rifles' 90%. Watch out for their notoriously slow reload.