Afforestation is the establishment of a forest or stand of trees (forestation) in an area where there was no recent tree cover. In comparison, reforestation means re-establishing forest that have either been cut down or lost due to natural causes, such as fire, storm, etc. There are three types of afforestation: Natural regeneration, agroforestry and tree plantations. Afforestation has many benefits. In the context of climate change, afforestation can be helpful for climate change mitigation through the route of carbon sequestration. Afforestation can also improve the local climate through increased rainfall and by being a barrier against high winds. The additional trees can also prevent or reduce topsoil erosion, floods and landslides. Finally, additional trees can be a habitat for wildlife, and provide employment and wood products.

Reforestation is the practice of restoring previously existing forests and woodlands that have been destroyed or damaged. The prior forest destruction might have happened through deforestation, clearcutting or wildfires. Two important purposes of reforestation programs are for harvesting of wood or for climate change mitigation purposes. Reforestation can also help with ecosystem restoration. One method for reforestation is to establish tree plantations, also called plantation forests. They cover about 131 million ha worldwide, which is 3 percent of the global forest area and 45 percent of the total area of planted forests.