Abstract Primary succession is the assembly of ecosystems on barren landscapes following severe disturbances that leave little or no biological legacy (lava flows, landslides and mine wastes). The assembly process involves colonisation of newly exposed substrates and subsequent interactions among the colonising plants, animals and soil microbes. Successional trajectories of sequential community replacement then develop, but some may diverge from nearby trajectories, making succession a challenging process to predict. Understanding how plant, animal and microbial communities develop under such extreme conditions is essential for restoration of damaged lands, as restoration is fundamentally the manipulation of successional trajectories by humans. Successional studies also provide insights into loss of biodiversity, climate change and the influences of invasive species on community dynamics. Key Concepts: Primary succession is the process of assembly of ecosystems on barren landscapes following severe disturbances that leave little biological legacy. Primary succession is difficult to predict because it is the net result of many interacting processes including dispersal, colonisation, species interactions and biotic responses to on‐going disturbances. Restoration is the attempt to manipulate succession and what is known about primary succession can be applied to the amelioration of severely disturbed habitats. Primary succession provides insights into biodiversity loss, climate change and the influences of invasive species.