If a particle in periodic motion moves back and forth (or to and fro) over the same path, then its motion it is called as vibratory or oscillatory. The examples of vibratory or oscillatory motion are:
1.The motion of a pendulum.
2.The motion of a spring fixed at one side, which is compressed or stretched and then released.
3.The motion of a violin string.
4.The motion of atoms in molecules or in a solid lattice.
5.The motion of air molecules as sound wave passes by.