Used mostly for motorcycles, and other smaller types of vehicles. Great on efficiency, with decent power. Pretty loud sometimes
Engine that runs on a heat source! Pretty cool in my opinion, works by the gas heating/expanding, then cooling to pull back the piston. Very quiet and used almost exclusively in submarines.
My personal favorite, can make a lot of power in small size with only 3 moving parts! However, they are pretty inefficient, the last car to use this was a Mazda RX-8.
Pretty common nowadays, it's what you'll find in your Hondas and Toyotas, fuel efficient, with enough power to keep you moving.
Used mostly in small aircraft for the propeller
Pretty interesting design, but not used widely since they are hard to make, and they cannot work at high RPMs
Air sucked in through the front and out the back with a controlled explosion in the middle. Great for large planes, and stuff.
Read more: http://imgur.com/gallery/eatFH