Succession refers to the process by which one ecological community replaces another over time, often following a disturbance or the creation of new habitats. It occurs in a series of stages, beginning with pioneer species that colonize barren or disturbed areas, followed by intermediate species, and eventually leading to a stable climax community. There are two main types of succession: primary succession, which starts on lifeless surfaces, and secondary succession, which occurs in areas where a disturbance has cleared an existing ecosystem but left the soil intact.