Polarisation
Polarization is a property of waves that can oscillate with more than one orientation. Electromagnetic waves such aslight exhibit polarization, as do some other types of wave, such as gravitational waves. Sound waves in a gas or liquid do not exhibit polarization, since the oscillation is always in the direction the wave travels.
Polarization happens when people become divided into contrasting groups. If a teacher lets the class vote on whether to have class outside or not, and half wants to stay and the other half wants to go, that issue caused polarization.
Wave propagation and polarization
Most sources of light are classified as incoherent and un polarized (or only "partially polarized") because they consist of a random mixture of waves having different spatial characteristics, frequencies (wavelengths), phases, and polarization states. However, for understanding electromagnetic waves and polarization in particular, it is easiest to just consider coherent plane waves; these are sinusoidal waves of one particular direction , frequency, phase, and polarization state. Characterizing an optical system in relation to a plane wave with those given parameters can then be used to predict its response to a more general case, since a wave with any specified spatial structure can be decomposed into a combination of plane waves. And incoherent states can be modeled stochastically as a weighted combination of such uncorrelated waves with some distribution of frequencies, phases, and polarizations.