The Rightly Guided Caliphs or The Righteous Caliphs (الخلفاء الراشدون al-Khulafā’u r-Rāshidūn) is a term used in Sunni Islam to refer to the first four Caliphs who established the Rashidun Caliphate. The concept of "Rightly Guided Caliphs" originated with the Abbasid Dynasty. It is a reference to the Sunni tradition, "Hold firmly to my example (sunnah) and that of the Rightly Guided Caliphs" (Ibn Majah, Abu Dawood).
The first four Caliphs who ruled after the death of Muhammad are often quoted as the Khulafah Rashidun.
The Rashidun were either elected by a council (see The election of Uthman and Islamic democracy) or chosen based on the wishes of their predecessor. In the order of succession, the rashidun were:
Hasan ibn Ali was appointed as Caliph in 661 following the death of Ali and is also regarded as a righteous ruler by Sunni Muslims, although he was recognized by only half of the Islamic state and his rule was challenged and eventually ended by the Governor of Syria, Muawiyah ibn Abi Sufyan.
Abu Bakr (Abdullah ibn Abi Quhafa) (Arabic: عبد الله بن أبي قحافة, Transliteration: ʿAbd Allāh ibn Abī Quḥāfah, c. 573 CE - 634 CE) also known as Abū Bakr as-Șiddīq (Arabic: أبو بكر الصديق) was a senior companion (Sahabi) and the father-in-law of the Islamic prophet Muhammad. He ruled over the Rashidun Caliphate from 632–634 CE 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, since the religious function and authority of prophethood ended with Muhammad's death according to Islam. He was called Al-Siddiq (The Truthful) and was known by that title among later generations of Muslims.
As a young man, Abu Bakr became a cloth merchant and he traveled extensively in Arabia and neighboring lands in the Middle East, through which he gained both wealth and experience. He eventually came to be recognized as the chief of his clan. On his return from a business trip to Yemen, he was informed that in his absence Muhammad had openly declared his prophethood. Not long after, Abu Bakr accepted Islam and was the first person outside the family of Muhammad to openly become a Muslim. He was instrumental in the conversion of many people to the Islamic faith and early in 623, Abu Bakr's daughter Aisha was married to Muhammad, strengthening the ties between the two men.