Abū Bakr (أبو بكر ;c. 573 AD-22 August 634), was a senior companion and—through his daughter Aisha—the father-in-law of the Islamic prophet Muhammad. Abu Bakr became the first openly declared Muslim outside Muhammad's family. Abu Bakr served as a trusted advisor to Muhammad. During Muhammad's lifetime, he was involved in several campaigns and treaties.
He ruled over the Rashidun Caliphate from 632 to 634 AD when he became the first Muslim Caliph following Muhammad's death. As caliph, Abu Bakr succeeded to the political and administrative functions previously exercised by Muhammad. He was commonly known as The Truthful Caliph (الصديق, As-Saddīq). Abu Bakr's reign lasted for 2 years, 3 months and 11 days ending with his death after an illness. He ruled over the Rashidun Caliphate from 632 to 634 AD when he became the first Muslim Caliph following Muhammad's death.