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 spread of Islam and was a close companion of the Prophet Muhammad. Umar is also recognized for implementing various reforms, including the establishment of a judicial system and welfare programs. His policies promoted justice and equality, making him a respected figure in Islamic history. He was assassinated in 644 CE, leaving a lasting legacy as a just ruler.