P90X is an exercise and diet program marketed on the Internet. Along with access to the workout plans, which are fairly traditional resistance training programs, you get videos and an online support forum.
P90X is a workout system developed by Tony Horton. The exercise program is based on muscle confusion. It is available for purchase to consumers on a set of dvds.
P90X is a 90 day dvd workout program that you can do in the comfort of your own home. All it takes is a pullup bar and a few dumbells or resistance bands.