Ballistics is the science that studies the motion of projectiles, such as bullets or missiles, after they are fired. It involves understanding how these objects travel through the air, their speed, trajectory, and the forces acting on them, like gravity and air resistance. There are three main types of ballistics: internal, external, and terminal. Internal ballistics focuses on the behavior of a projectile inside a firearm, while external ballistics examines its flight through the air. Terminal ballistics looks at the effects of a projectile when it hits a target, such as its penetration and damage.