What stays constant in ideal projectile motion?

In ideal projectile motion, the horizontal velocity remains constant throughout the flight of the projectile. This occurs because there is no horizontal force acting on the projectile (assuming air resistance is negligible). Since there is no net force to change the horizontal velocity, it remains steady from launch until impact.

As the projectile ascends and descends, it experiences vertical motion influenced by gravity, which affects the vertical velocity. The overall acceleration due to gravity acts downwards at a constant rate; however, it only affects the vertical component of the motion, not the horizontal. Similarly, while forces such as gravity are acting on the projectile, they do not influence the horizontal motion, thereby reinforcing that the horizontal velocity remains consistent in the absence of opposing lateral forces.