We know that a frame of reference is needed to locate the position of any object. For that, we choose the rectangular coordinate system of three mutually perpendicular axes that are $x$, $y$, and $z$ axis. The point of intersection of these three axes is called Origin ‘O’ and is considered as the Reference Point.
The $x$, $y$, and $z$ coordinates describe the position of an object with respect to the coordinate system. To measure time, we need a clock. The coordinate system along with a clock constitutes a Frame of reference. So, the frame of reference is a coordinate system, with a clock w.r.t. which, an observer can describe the position, displacement, etc. of an object.
Frames of reference are of two types:-
- Inertial frame of reference:- These are the frame of reference in which Newton’s First Law of Motion is applicable.
- Non-Inertial frame of reference:- These are the frame of reference in which, Newton’s first law of motion is not applicable
There is a more exciting background to the idea of frame of reference. It has to do with the characterization of the real 3-D space with a set of orthogonal unit vectors for the measurement purpose. At each point in space, there could be created such a orthogonal system. The condition is that the function in such a space is continuous and differentiable. For example the usual Cartesian space unit vector triad i.e. {i,j,k} is a natural frame field on [\itex]R^3[/itex]. The inertial frame and non-inertial frame could be handled by the method of moving frame.