What are FET's used for?

FET's or field effect transistors' can be used for a variety of purposes from audio to power control. Unlike a regular (bipolar) transistor, they are more efficient and responsive to input voltages. There are several benefits to using FET's and are way too numerous to list here, but they are a very good type of transistor where the applications require additional sensitivity. I've used many different types and prefer using them whenever possible for my personal projects.