Robotics makes great use of motors. They rotate and do things you expect your robot to do. Pot a ball, hold a can or salute you! Here's a list of three different types of motors that you'll use when creating your robot. These three motors cover a HUGE variety of requirements: speed, torque, accuracy, etc.

The DC Motor

The most used motor ever. You supply power, it turns. Your reverse the polarity and it turns in the opposite direction.If you're getting started with robotics, chances are you'll encounter these a lot!

There are lots of flavours of DC motors available: brushed, brushless, homopolar, etc. You'll usually use the brushed DC motor and in some cases the brushless DC motor (if you want extremely high efficiency).

Pros about DC motors:

1. They have high speeds
2. Can produce high torques (with appropriate gears)
3. Very simple to use!

Cons of DC motors:

1. Very inaccurate
2. Do not stop immediately due to inertia
3. They can actually burn out.

The Stepper Motor

Steppers are also a type of DC motor. Controlling these is not as  trivial as powering them. You need to power multiple coils in a synchronized manner to create rotational motion.

Pros about Steppers:

1. Very accurate
2. Available for different levels of accuracies (from 45 degrees to 0.1 degrees)

Cons of Stepper motors:

1. Slow
2. Low torque
3. Using them is complex

The Servo Motor

Servos don't produce rotational motion. They usually produce linear motion. These are used in humanoid robots.

Pros about Servos:

1. Decent accuracy
2. High torque

Cons of Servos

1. Very expensive
2. Using them is complex