A projectile is any object projected by some means that continues to move due to its own inertia. Projectiles move in two dimensions with both horizontal and vertical velocity components. The horizontal velocity is constant, while the vertical velocity changes due to gravity. Together the components produce the trajectory path, which is parabolic. For horizontally launched projectiles with no initial vertical velocity, the horizontal velocity remains constant while the vertical acceleration is due to gravity. For vertically launched projectiles, the total velocity must be broken into horizontal and vertical components using trigonometry. The kinematic equations can then be applied to each component to solve for time, displacement, or other variables.