Agenda 21 is an action plan of the United Nations (UN) related to sustainable development.
Number 21 in Agenda 21 means the 21st century.
It is a non-binding voluntarily implemented agreement.
It was the result of the Earth summit (also known as Rio summit) 1992.
It is a blueprint of action to be taken globally, nationally, and locally of organizations of the United Nations, national governments, and major groups in every area in which humans directly affect the environment.