Omnidirectional microphones are microphones that hear everything that's going on around them. They are equally sensitive to sound from all directions. ... Cardioid microphones “listen” to sound from the front and reject sound from the rear.

There are three basic types: omnidirectional, unidirectional and bidirectional (also called figure-of-eight)

Directionality refers to the sensitivity relative to the direction or angle of sound arriving at the microphone. Directionality is usually plotted on a graph referred to as a polar pattern. A polar pattern graph shows the variation in sensitivity as you move 360 degrees around the microphone

Dynamic Microphones. Large Diaphram Condensor Microphones. Small Diaphram Condensor Microphones. Ribbon Microphones.