Ecological succession is the process through which an ecosystem evolves and changes over time. It involves a series of predictable and gradual changes in the composition of species and the structure of the ecosystem. There are two main types of ecological succession: primary succession, which occurs on a newly formed or exposed habitat with no soil present, and secondary succession, which occurs on a previously inhabited habitat that has been disturbed or disrupted. The process of ecological succession typically involves pioneer species colonizing the area first, followed by a series of changes in species composition until a stable climax community is reached. This process can take hundreds to thousands of years to complete, depending on the specific conditions of the ecosystem.