Explanation:
The concept of sustainable development was first officially defined and explained in the Brundtland Commission Report, also known as "Our Common Future." The Brundtland Commission, officially called the World Commission on Environment and Development, was established in 1983 by the United Nations General Assembly. The commission was chaired by Gro Harlem Brundtland, the former Prime Minister of Norway, and consisted of 21 members from various countries.

The report was published in 1987 and provided a comprehensive understanding of sustainable development. It defined sustainable development as "development that meets the needs of the present without compromising the ability of future generations to meet their own needs."

Key Points:
- The Brundtland Commission Report, published in 1987, was the first official and comprehensive explanation of sustainable development.
- The report was prepared by the World Commission on Environment and Development, chaired by Gro Harlem Brundtland.
- The report defined sustainable development as development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
- It emphasized the importance of considering environmental, social, and economic factors together to achieve sustainable development.
- The report highlighted the challenges of population growth, poverty, environmental degradation, and resource depletion.
- It called for global cooperation, policy changes, and the integration of sustainability principles into decision-making processes.
- The report also emphasized the need for equity, social justice, and the eradication of poverty as essential components of sustainable development.
- It gained significant international attention and laid the foundation for subsequent discussions and actions on sustainable development.
- The Brundtland Commission Report was a crucial milestone in raising awareness about the importance of sustainability and influencing policy-making and development strategies worldwide.

Therefore, the Brundtland Commission Report, also known as "Our Common Future," was the first official document that explained the concept of sustainable development in detail.