There are three main factors that affect wave formation: wind velocity, fetch, and duration.
Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest.
To answer this you must first know the definition of a wave. A wave is an oscollation (something that goes back and forth repeatedly) in a medium. A medium is something that the wave travels through, for example, the sound that we hear travels through air, that's to say air is the medium. The cause of a wave is usually caused by introducing energy into a medium. for example, if you shake an electron you introduce energy into the electromagnetic medium. Or if you smack your hands together you introduce energy into the air medium. The energy you introduced travels through the medium. After you shook the electron you gave the electromagnetic medium energy.
