A green wall is a vertical built structure intentionally covered by vegetation. Green walls include a vertically applied growth medium such as soil, substitute substrate, or hydroculture felt; as well as an integrated hydration and fertigation delivery system. They are also referred to as living walls or vertical gardens, and widely associated with the delivery of many beneficial ecosystem services.

Greening is the process of transforming living environments, and also artifacts such as a space, a lifestyle or a brand image, into a more environmentally friendly version. The act of greening generally involves incorporating more environmentally friendly systems into one's environment, such as the home, work place, and general lifestyle.