The problems related to the process of industrialisation such as biodiversity depletion, climate change and a worsening of health and living conditions, especially but not only in developing countries, intensify. Therefore, there is an increasing need to search for integrated solutions to make development more sustainable. The United Nations has acknowledged the problem and approved the “2030 Agenda for Sustainable Development”. On 1st January 2016, the 17 Sustainable Development Goals (SDGs) of the Agenda officially came into force. These goals cover the three dimensions of sustainable development: economic growth, social inclusion and environmental protection. The Encyclopedia of the UN Sustainable Development Goals comprehensively addresses the SDGs in an integrated way. It encompasses 17 volumes, each one devoted to one of the 17 SDGs. This volume addresses SDG 15, namely "Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss" and contains the description of a range of terms, which allow a better understanding and foster knowledge. Concretely, the defined targets are: Ensure the conservation, restoration and sustainable use of terrestrial and inland freshwater ecosystems and their services, in particular forests, wetlands, mountains and drylands, in line with obligations under international agreements Promote the implementation of sustainable management of all types of forests, halt deforestation, restore degraded forests and substantially increase afforestation and reforestation globally Combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world Ensure the conservation of mountain ecosystems, including their biodiversity, in order to enhance their capacity to provide benefits that are essential for sustainable development Take urgent and significant action to reduce the degradation of natural habitats, halt the loss of biodiversity and protect and prevent the extinction of threatened species Promote fair and equitable sharing of the benefits arising from the utilization of genetic resources and promote appropriate access to such resources, as internationally agreed Take urgent action to end poaching and trafficking of protected species of flora and fauna and address both demand and supply of illegal wildlife products Introduce measures to prevent the introduction and significantly Reduce the impact of invasive alien species on land and water ecosystems and control or eradicate the priority species Integrate ecosystem and biodiversity values into national and local planning, development processes, poverty reduction strategies and accounts Mobilize and significantly increase financial resources from all sources to conserve and sustainably use biodiversity and ecosystems Mobilize significant resources from all sources and at all levels to finance sustainable forest management and provide adequate incentives to developing countries to advance such management, including for conservation and reforestation Enhance global support for efforts to combat poaching and trafficking of protected species, including by increasing the capacity of local communities to pursue sustainable livelihood opportunities Editorial Board Alexandra Aragão, Desalegn Yayeh Ayal, Ayansina Ayanlade, Anabela Marisa Azul, Adriana Consorte-McCrea, Muhammad Farooq, Ana Catarina Luz, María P. Martín, Sharif A. Mukul, Nandhivarman Muthu, Robert Russell Monteith Paterson, Isabel Ruiz-Mallén