MOSFETs are the most common transistors used today. They are switches that can be used an Arduino, BeagleBone, or Raspberry Pi. This is part 2 of a 2 part series, which covers MOSFETs. (Part 1 Covered BJTs).
When it comes down to it, MOSFETs are pretty complicated devices. This video will cover the basics of what you need to use them in your circuit, including calculating if you need a heat sink or not.