If a coordinate system is attached to a rigid body and one describe the position of any particle relative to it, then such coordinate system is called

The frame of reference:

The motion of different bodies can be conveniently described if we imagine a coordinate system attached to a rigid body and the positions of different bodies in space can be described with respect to it, then such a coordinate system is called the frame of reference. 

Within a frame of reference, we set up a coordinate system that is used to measure the position of an object and choose the origin accordingly.

There are two types of frame of reference:

Inertial frame of reference: The frame of reference having zero acceleration is called the Inertial frame of reference.

• This frame of reference will be either in rest or will be moving with a constant velocity.
• Newton’s law is valid in this frame of reference.

The non-inertial frame of reference: The frame of reference having non-zero acceleration is called the non-inertial frame of reference.

• Newton’s law is not valid in this frame of reference.
• For example: If we are observing an object from a freely falling object then this will be a non-inertial frame of reference because the freely falling body has some acceleration.

Space-time reference system:

• For the location of any event in a frame of reference or coordinate system, we require the position and time of occurrence of the event.
• So, in this case of the rectangular or Cartesian coordinate system, four coordinates are required to describe the position that is (x,y,z,t)(x,y,z,t).
• The reference system employed for this purpose is called a space-time frame of reference.