In games, you want sprite movement to feel responsive and smooth. If you only move the sprite when a key is pressed or released, the movement will be choppy, as the sprite will jump by a fixed amount each time you press a key. Instead, you should track the state of each relevant key—whether it is currently pressed or not. This way, you can update the sprite's position every frame in your game loop, creating continuous movement as long as the key remains held down.

Handling multiple keys is also important for allowing diagonal movement, such as moving up and right at the same time. By checking the state of each key independently inside your game loop, you can combine directions naturally and give the player full control over the sprite's movement.