So far we have only been dealing with reference points or reference frames that are stationary. A moving reference frame refers to a frame of reference that is itself in motion relative to another perspective, often called a stationary reference frame. To understand this, let’s break it down with an example:

Imagine a scenario where you are driving in a car at 15m/s past a bunch of stationary pedestrians on the sidewalk next to you:

From the pedestrian point of view, you and the car are moving at 15m/s forward. The pedestrian would be considered the stationary reference frame in this case

From your point of view, the car would be stationary as you are moving together with the car; however, the pedestrian would be moving 15m/s backward. You would be considered the moving reference frame in this case