The Sino-Portuguese Joint Declaration is an agreement signed on April 26, 1987, between the governments of China and Portugal. It outlines the terms for the transfer of sovereignty over Macau from Portugal to China, which took place on December 20, 1999. The declaration emphasizes the principle of "one country, two systems," allowing Macau to maintain its own legal and economic systems for 50 years after the handover. The agreement also guarantees the protection of the rights and freedoms of the people in Macau, ensuring that its way of life would remain unchanged. This framework was designed to foster stability and continuity in the region, promoting cooperation between China and Portugal while respecting the unique cultural identity of Macau.