In optics an physics, a wavefront is the locus (a line, or, in a wave propagating in 3 dimensions, a surface) of points having the same phase. Since infrared, optical, x-ray and gamma-ray frequencies are so high, the temporal component of electromagnetic waves is usually ignored at these wavelengths, and it is only the phase of the spatial oscillation that is described. Additionally, most optical systems and detectors are indifferent to polarization, so this property of the wave is also usually ignored. At radio wavelengths, the polarisation becomes more important, and receivers are usually phase-sensitive. Many audio detectors are also phase-sensitive.