STATIONARY WAVES
When two waves of equal amplitude and frequency traveling in opposite directions meet each other, they will certain points along their path, where the sum of displacements will always be zero. These places are called nodes, the point midway between adjacent nodes is an antinode, here there is double the amplitude of a single wave. Standing waves can be observed in strings under tension and air colomns. A string or air colomn has various modes of vibrating, these are known as harmonics.

Comparisons

	Stationary	Progressive
in one wavelegthm, particles are	divided into two sets of particles with same phases, the sets are &pi out of phase	all at different phases
amplitudes in one wavelength	all different	all the same