Apexogenesis is a pulp therapy procedure used to encourage continued development of an immature permanent tooth with an open apex. It aims to maintain pulp vitality to allow further root development and maturation. The procedure involves removing infected or decayed dental tissue, then placing a material like calcium hydroxide or MTA over the exposed pulp tissue. This helps stimulate the formation of a dentinal bridge and continued root development. The patient is monitored over time to check for successful root formation and healing.