Projectile motion is a form of motion where an object moves in a parabolic path; the path that the object follows is called its trajectory. Projectile motion only occurs when there is one force applied at the beginning of the trajectory, after which the only interference is from gravity. So, the trajectory is influenced by gravity and also by the air resistance.
A projected object moves under the influence of gravity (acceleration at 9.8 m/s squared). The movement of the projected object takes a parabola shape, that is it undergoes vertical and horizontal motion.
