To increase the sense of movement and depth, we are going to use a technique called parallax scrolling. This means that objects will move at different speeds based on their distance from the viewer. In real life, you can see this phenomenon when you are riding in a train or a car. When looking out of the side window, you will notice that objects that are close to the vehicle seem to be moving past a lot faster than objects that are further in the distance. Objects on the horizon hardly seem to move at all.

This relative movement is what we perceive as depth or distance. It allows us to guess the three-dimensional proportions of a space. We are going to simulate that 3D effect with our 2D sprites to make the scene a bit more realistic and engaging.