MCMAP is the Marine Corps Martial Arts Program. It is a synthesis of martial arts adapted into a combatives system for use in combat gear, while fatigued and under stress, allowing for a full range of situationally appropriate use-of-force responses. It includes unarmed, knife, bayonet, rifle, baton, and improvised weapon training, in addition to study of warrior cultures, character and values training, body hardening, and PT and mental toughness training.
There is a basic belt system (tan, grey, green, brown, several degrees of black), with tan belt being achieved in boot camp by all Marines, grey belt being expected of all Marines before becoming an NCO, and green belt being expected of all infantry Marines.
The system is often knocked because someone sees a tan belt class in boot camp learning a (poor) breakfall, or some kid gets in a bar fight and gets his ass kicked, but those who continue their education in MCMAP are for the most part extremely aggressive and well trained fighters.