Simple Harmonic Motion and Conditions- What is Simple Harmonic Motion?

Simple Harmonic Motion:

Simple Harmonic Motion is a special kind of Vibratory/Oscillatory Motion in which acceleration of the body is directly proportional to the displacement from the mean position and is always directed towards the mean position is called Simple Harmonic Motion.

What are conditions for simple Harmonic Motion:

There are three conditions must fulfill by a body executing simple Harmonic Motion 

1. Acceleration of of the body must be directly proportional to the displacement from the mean position.
2. Acceleration of the body must be directed to the mean position.
3. System should be frictionless and body executing simple Harmonic Motion must have inertia and restoring Force.