Sustainable development seeks to meet the needs of the present without compromising the ability of future generations to meet their own needs. It requires preserving ecological balance, respecting environmental limits, and ensuring rational use of resources. The concept has evolved since the 1970s, with key milestones including the UN Stockholm Conference in 1972, the Brundtland Commission report in 1987 defining sustainable development, and the Rio Earth Summit in 1992 establishing principles of sustainable development.