Electret microphones are the most commonly used microphones today. Every cellphone and laptop has one embedded into it, and many studio microphones are also electrets. They can have an extremely wide frequency response (from 10Hz to 30kHz ), and typically cost less than a dollar. They are also very small and quite sensitive. Despite these good characteristics, they can also have a few drawbacks, such as a high noise floor, high distortion, and uneven frequency response. We will dissect an electret microphone, explain how it works, and talk about the reasons for its various attributes.