Why is a frame of reference required?

(N/A) In order to specify the position of an object,we need to use a reference point and a set of axes. It is convenient to choose a rectangular coordinate system consisting of three mutually perpendicular axes,labeled $X$,$Y$,and $Z$-axes.
The point of intersection of these three axes is called the origin $(O)$ and serves as the reference point.
The coordinates $(x, y, z)$ of an object describe the position of the object with respect to this coordinate system.
To measure time,we position a clock in this system.
If one or more coordinates of an object change with time,we say that the object is in motion. Otherwise,the object is said to be at rest with respect to this frame of reference. The choice of a set of axes in a frame of reference depends upon the situation. For example,for describing motion in one dimension,we need only one axis. To describe motion in two or three dimensions,we need a set of two or three axes.