How do you determine if a body is moving?

Mechanical movement is a change in the position of the body relative to other bodies. The body, relative to which the change in the position of the investigated body is considered, is called the reference body. With respect to some bodies, the investigated body can change its position in different ways, move. Relative to other bodies, do not change their position, is at rest.
If the body changes its position relative to other bodies, then it is moving. If it does not change its position, then it does not move.