Do gun barrels have grooves (rifling)?

Yes, that's correct. The groove you're referring to is called "rifling." Rifling consists of a series of grooves and lands (the raised portions between the grooves) that are meticulously cut or formed into the barrel of a firearm. This design imparts a spin to the bullet as it travels down the barrel and exits, which stabilizes the projectile in flight, increasing accuracy and range. Not all firearms have rifled barrels; smoothbore barrels, which lack rifling, are typically found in shotguns and some older firearms.