This document discusses microphone polar patterns, which refer to how sensitive a microphone is to sound from different directions. The three main polar patterns covered are omnidirectional, bidirectional, and unidirectional. Omnidirectional microphones pick up sound equally from all directions, bidirectional microphones pick up sound from the front and back but reject the sides, and unidirectional microphones like cardioid, supercardioid, and hypercardioid primarily pick up sound from the front while rejecting sounds from other directions to varying degrees. The document provides examples of microphones with different polar patterns and tips on choosing a polar pattern based on the recording application and desired sound.