Waves are the things that we see when we we go to a beach.
The highest point of a wave is called as a crest of the wave and the lowest part of a wave is called its trough.
There are two kinds of waves:transverse and longitudinal
Transverse waves are when particles move perpendicular to the motion of the wave, example: all electromagnetic waves
Longitudinal Waves are when particles moves parallel to the motion of the wave, example waves seen in sea and sound waves