The 1.3 liter 2rotor wankel motor has 3 basic moving parts: 2 rotors that rotate around an eccentric shaft (crank shaft for comparison, if you will). There are no pistons, valves, connecting rods, camshafts or cams. The block consists of 5 slices, so to speak, called intermediate, rotor, and side housings. it looks like this:
side housing|rotor|intermediate|rotor|side housing|
Check out the detailed explanation here:
http://travel.howstuffworks.com/rotary-engine.htm
basically, it has a weight/less moving parts advantage over a piston motor. downside is initial lack of torque, and the motor cannot sustain as much abuse due to smaller margin of error. ie. you can overboost a piston motor and it'll survive. on a rotary, it can be a deadly result for the block