Wavelength is the distance between identical points in the adjacent cycles of a waveform signal propagated in space or along a wire. In wireless systems, this length is usually specified in meters, centimeters, or millimeters.
Wavelengths are an important factor in Wi-Fi networks. Wi-Fi operates at five frequencies, all in the gigahertz range: 2.4 GHz, 3.6 GHz, 4.9 GHz, 5 GHz and 5.9 GHz. Higher frequencies have shorter wavelengths, and signals with shorter wavelengths have more trouble penetrating obstacles like walls and floors.
As a result, wireless access points that operate at higher frequencies with shorter wavelengths, often consume more power to transmit data at similar speeds and distances achieved by devices that operate at lower frequencies, with longer wavelengths.