Reforestation is the deliberate or natural re-establishment of forest ecosystems on land where tree cover has been removed or significantly reduced. As a research field, it investigates the ecological processes, socio-economic factors, and technical methodologies required for successful forest restoration, encompassing planning, implementation, and long-term monitoring of stand development and ecosystem function. Its significance is rooted in its critical role for biodiversity conservation, climate change mitigation through carbon sequestration, watershed protection, and the sustainable provision of forest resources.