King João III of Portugal reigned from 1521 to 1557. He was the son of King Manuel I and continued the expansion of the Portuguese Empire, focusing on overseas territories in Africa, Asia, and Brazil. His reign is marked by the establishment of the Inquisition in Portugal, which aimed to maintain Catholic orthodoxy. João III's rule also saw significant cultural developments, including the promotion of the Portuguese Renaissance. He supported the arts and sciences, fostering a period of exploration and trade. His efforts helped solidify Portugal's status as a major maritime power during the Age of Discovery.