First, we'll go over a few common servos and motors that you'll run into. But first, for those who are new to this, let's look at a quick description of motors and servos.
A motor (or an electrical motor for our purposes) converts electrical energy to motion. Electricity goes in, motion comes out. This motion is output as a rotation motion; one of the most common uses of electronic motors is to turn wheels. Note that while you can control the speed of a motor by controlling the power being input, you cannot change the position of a motor precisely.
This is where servos come in. Servos use electricity to move to a set point—most commonly in an arc of 180 degrees. However, there are some servos that can rotate 360 degrees. We'll discuss these in a moment. Servos are technically specialized motors, and while motors are used to propel projects, servos are used to control them.