Caliph Ali, also known as Ali ibn Abi Talib, was the cousin and son-in-law of the Prophet Muhammad. He became the fourth caliph of the Rashidun Caliphate in 656 CE and is revered in both Sunni and Shia Islam. His leadership was marked by significant challenges, including civil strife and the First Fitna, a series of conflicts among Muslims. Ali is known for his wisdom, bravery, and commitment to justice. He played a crucial role in the early Islamic community and is often celebrated for his eloquent speeches and writings, including the famous Nahj al-Balagha, a collection of his sermons and letters.