Abu Bakr (l. 573-634 CE, r. 632-634 CE) was an early convert of Islam; he was a close friend and confidant of the Islamic Prophet Muhammad, and became the first caliph of the Islamic empire – a successor to Muhammad's temporal position but not a prophet himself, as according to Islamic sources, that had ended with Muhammad (l. 570-632 CE). He helped his friend Muhammad through thick and thin in his mission and stayed by his side until the end of his days. After the death of the Prophet, he became the first of the four caliphs of the Rashidun Caliphate – as it is called by Sunni Muslims. In his brief reign of two years, he reunited the Arabian Peninsula and started conquests in Syria and Iraq, which were later carried on successfully by his successors until 656 CE when the first Islamic civil war, the First Fitna (656-661 CE) erupted and expansion was temporarily halted. It was also during Abu Bakr's reign that the revelations dictated by Muhammad were compiled in the form of the Islamic holy scripture: the Quran.
This is a companion discussion topic for the original content at https://www.worldhistory.org/Abu_Bakr/.