Caliph Umar, also known as Umar ibn al-Khattab, was the second caliph of the Rashidun Caliphate, serving from 634 to 644 CE. He is known for his strong leadership and administrative skills, which helped expand the Islamic empire significantly during his reign. Umar played a crucial role in the early conquests of Persia and Byzantine territories, establishing a vast empire. Umar is also recognized for implementing various reforms, including the establishment of a judicial system and welfare programs for the poor. His governance emphasized justice and accountability, earning him respect among his people. He was assassinated in 644 CE, leaving a lasting legacy in Islamic history.