Islam is a religion of peace, harmony and equality, to preach this Holy Religion, Allah Almighty sent his beloved Prophet Hazrat Muhammad (S.A.W). He (S.A.W) preached Islam, facing great hardships but be remained patient and  submitted his problems to the Will of Allah..Allah Almighty wanted his religion to remain alive till the day of Judgment.  So after Holy Prophets death, his four  most beloved followers, friends and companions become the caliphs of Islam who were Hazrat Abu Bakr (R.A). Hazrat Umer (R.A), Hazrat Usman (R.A) and HazratAli(RA).
HazratAbu Bakr(R.A):
HazratAbu Bakr (R.A) was the first Caliph of Islam after Prophet’s (S.A.W) death. He was the first among men who embraced Islam. He helped Prophet (S.A.W) in every way and also participated in wars. Hazrat Abu Bakr (R.A) served as trusted advisor and a close friend of Muhammad (S.A.W). During the lifetime of Muhammad (S.A.W) he participated in several campaigns such as battle of Trench, the Invasion of Banu Qurayza, migration towards Madinah. Hazrat Abu Bakr (R.A) was known for favouring truth. That’s why he was also cal1ed Hazrat Abu Bakr Saddique (RA). He died in 64OAD.
Hazrat Umer (R.A):
Hazrat Urner (R.A) was the most powerful of the four caliphs and one of the most powerful and influential Muslim rules in history.  He is known for his best justice that won him the title of Al Farooq. Under the supervision of Hazrat Umer (R.A)  the Islamic Empire expended at an unprecedental rate, he ruled the whole Persian and Roman Empires, he was a great leader and pious man.
Hazrat Usman (R.A):
Hazrat Usman (R.A) was one of the companions of Prophet (S.A.W). He played a major role in early Islamic history as the third caliph of Islam. One of Hazrat Usman’s (R.A) noble achievements was the economic reforms he introduced. He also unified Muslim Ummah on one script and accent of Holy Quran. That is why he (R.A) is called Jaznia ul Quran. Hazrat Usman (R.A) was martyred in 656 A.D.
Hazrat Ali(R. A):
Hazrat Ali (R. A) was the son of Abu Talib. Hazrat Ali (R.A) was also the cousin and son-in-law of Prophet (S. A. W). He was the first among children who embraced Islam. Hazrat Ali (R.A) was a very brave man and took part in every war fought during his life time as a Muslim. He defended the Holy Prophet (S.A.W) a lot and fought by the will of Allah and to spread Islam. Hazrat Ali (S.A.W) is respected for his courage, knowledge, strong belief, honesty and devotion to Islam. Hazrat Ali (R.A) was martyred during the month of Ramadan.
At the end we acknowledge that all caliphs of Islam followed the same teachings. Our Holy Prophet (S.A. W.W) .Once said “All my companions are like stars, whomever you follow, you will find the right path.” May Allah give us strength to follow the teachings of Holy Prophet (S. A. W) and his Sahaba (R.A).