Biological succession is the process by which ecosystems change and develop over time. It involves a series of stages where different species of plants and animals gradually replace one another in a specific area. This can occur after a disturbance, such as a fire or flood, or in a new environment, like a volcanic island. There are two main types of succession: primary succession and secondary succession. Primary succession begins in lifeless areas, while secondary succession occurs in areas where a disturbance has cleared out existing life but soil remains. Both types lead to a more complex and stable ecosystem over time.