Omar 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 significant contributions to the expansion of the Islamic empire. Under his rule, the territories of Syria, Egypt, and Persia were conquered, greatly increasing the influence of Islam. Omar was also recognized for his administrative reforms and the establishment of a judicial system. He is credited with creating the Islamic calendar and promoting social justice, including rights for women and non-Muslims. His legacy continues to impact Islamic governance and law today.