Wave speed is the rate at which a wave propagates through a medium. It depends on both the wavelength (the distance between successive wave peaks) and the frequency (how many waves pass a point per second). The fundamental relationship v = λf shows that wave speed equals wavelength times frequency.

Different types of waves travel at different speeds depending on the medium. Electromagnetic waves (like light) travel fastest in a vacuum, while mechanical waves (like sound) require a physical medium and travel at speeds determined by the medium's properties such as density and elasticity.