The general concept that Israel would return land (the amount subject to negotiations) occupied during the Six-Day War (1967) in exchange for peace, recognition, and normalization of relations with the Arab states. The principle was enshrined in United Nations Security Council Resolutions 242 (1967) and 338 (1973). It was accepted as the framework for Arab-Israeli negotiations by all parties to the Madrid Middle East Peace Conference of 1991.
Historical Dictionary of Israel. Bernard Reich David H. Goldberg. Edited by Jon Woronoff..