P90X is a home fitness program created by Tony Horton that combines strength training, cardio, yoga, and flexibility exercises. The program lasts 90 days and is designed to improve overall fitness through a variety of workouts that target different muscle groups. The workouts are structured in a way that promotes muscle confusion, which helps prevent plateaus and keeps the body challenged. P90X includes a series of DVDs, a nutrition guide, and a workout calendar to help users stay on track and achieve their fitness goals.