Complex sentence: A prison gang is an inmate organization that operates within a prison system, that has a corporate entity, exists into perpetuity, and whose membership is restrictive, mutually exclusive, and often requires a lifetime commitment.
Split into simpler sentences: A prison gang is an inmate organization that operates within a prison system. It has a corporate entity, exists into perpetuity, and its membership is restrictive, mutually exclusive, and often requires a lifetime commitment.