Waves can transfer energy from one place to another through either transverse or longitudinal vibrations. Transverse waves vibrate perpendicular to the direction of energy transfer, while longitudinal waves vibrate parallel to it. Waves are described by their amplitude, wavelength, and frequency - with amplitude being the maximum displacement from equilibrium, wavelength the distance between equivalent points on consecutive waves, and frequency the number of waves passing a point per second. The relationship between wavelength, frequency, and wave speed is defined by the wave equation.