Basic Push-Up (Training with Your Own Body Weight)

"Also referred to as the press up, the Push-Up is possibly the most classic of all strength training exercises. This exercise develops your upper body, particularly the pectoralis major muscles or pectorals, and the triceps brachii muscles or triceps. Push-Ups are also a staple in military training."

http://www.abc-of-fitness.com/training-own-body-weight/basic-push-ups.asp