Motors are the "legs" of an NXT robot; without them, it really can't go any where. There are three motor ports available, A, B, and C. Generally in NXT we like to have the motor on the right as B, the motor on the left C, and our extra motor as A. It's preferable to mount motor A at the front and center of your robot to easily place attachments on the motor and enable successful missions. Sort of like the picture shown below!
