Primary succession is the process by which ecosystems develop in an area where no soil exists, such as after a volcanic eruption or glacial retreat. It begins with the colonization of pioneer species, like lichens and mosses, which can survive in harsh conditions and help break down rock into soil over time. As soil builds up, more complex plants, such as grasses and shrubs, can grow, followed by larger plants like trees. This gradual change leads to a more diverse and stable ecosystem, eventually resulting in a climax community, which is a mature and balanced environment.