Abdallah ibn Abi Quhafah (Arabic: عبد الله بن أبي قحافة; c. 573 CE – 23 August 634 CE), popularly known as Abu Bakr (Arabic: أبو بكر), was a companion and, through his daughter Aisha, a father-in-law of the Islamic prophet Muhammad, as well as the first of the Rashidun Caliphs.
Initially a rich and respected businessman, Abu Bakr later became one of the first converts to Islam and extensively contributed his wealth in support of Muhammad's work. He was among Muhammad's closest companions, accompanying him on his migration to Medina and being present at a number of his military conflicts, such as the battles of Badr and Uhud.
Following Muhammad's death in 632, Abu Bakr succeeded in the leadership of the Muslim community as the first Rashidun Caliph. During his reign, he overcame a number of uprisings, collectively known as the Ridda wars, as a result of which he consolidated and expanded the rule of the Muslim state over the entire Arabian peninsula. He also commanded the initial incursions into the neighbouring Sassanian and Byzantine empires, which in the years following his death, would eventually result in the Muslim conquests of Persia and the Levant. Abu Bakr died of illness after a reign of 2 years, 2 months and 14 days.
Source: Wikipedia, "Abu Bakr", available under the CC-BY-SA License.