What is standing or stationary waves ?

Hint: Standing waves are also known as the stationary wave, it is the combination of two waves which are moving in the opposite directions both of have the same amplitude and the frequency.

Complete answer:
The waves moving can result in the interference resulting when the waves are superimposed and in the either added together or else cancel each other. When the waves are moving in the same direction, the interference produced will result in the traveling wave. While, when the waves are moving in the opposite direction interference produces an oscillating wave fixed in the space.

In simple words, the stationary waves are produced by superposition of two progressive waves of equal amplitude and frequency, travelling with the same speed in the opposite directions. In stationary waves, the crests and troughs are formed in the transverse stationary waves and the compression and the rarefaction are formed in the longitudinal stationary waves. Stationary Waves neither move forward nor backward in the medium that is they will not advance in the medium.

All the particles of the medium vibrate except at the nodes such that amplitude of the vibration is different for the different particles. At nodes the amplitude is minimum or zero and the maximum at anti-nodes. Stationary waves do not transport energy.

Note: Don’t get confused between the stationary waves and the progressive waves. In the stationary waves, all particles oscillate at the same frequency except those at the nodes while for the progressive waves, all the particles oscillate with the same frequency.