Intergenerational equity in economic, psychological, and sociological contexts, is the concept or idea of fairness or justice in relationships between children, youth, adults and seniors, particularly in terms of treatment and interactions. It has been studied in environmental and sociological settings (Source: Wikipedia)

Intragenerational equity is concerned with equity between people of the same generation and aims to assure justice among human beings that are alive today, as reflected in Rio Principle 6, mandating particular priority for the special situation and needs of developing countries, particularly the least developed and those most environmentally vulnerable. (Oxford Handbook of International Environmental Law, chapter 1 - Equity, D. Shelton, 2008)

The right to development must be fulfilled so as to equitably meet developmental and environmental needs of present and future generations (Rio Principle 3).

The special situation and needs of developing countries, particularly the least developed and those most environmentally vulnerable, shall be given special priority. International actions in the field of environment and development should also address the interests and needs of all countries. (Rio Principle 6)