Most snakes have one functional lung and they use there muscles to take it air and this is how they breath. Snakes live everywhere in the world except Antarctica. You can find more information here: http://en.wikipedia.org/wiki/Snake
1 Additional Answer
Snakes breath through their nostrils and have one large lung. The right lung accounts for 1/3 of their body. They are able to breath while they eat because of a windpipe you can see in their lower mouth.