1st infallible: Prophet Muhammad (PBUHH) 
Name: Muhammad.
Title: al-Mustafa.
Agnomen: Abu'l-Qasim.
Father: Abdullah ibn Abdil-Muttalib. (Abdil-Muttalib was the tribal leader of Banu Hashim and was also the guardian of the Ka'bah. Among his ten sons, Abdullah was the father of the Holy Prophet and Abu Talib was the Prophet's uncle and the father of Imam Ali.)
Mother's name: Aminah bint Wahb.
Birth: Born in Mecca on Friday, 17th Rabiu'l-awwal, in the Year of Elephant.
Death: Died at the age of 63 in Medina on Monday, 28th Safar, 11 AH; buried in his house which was a part of the his mosque, in Medina.

Lineage
The Holy Prophet said: “The first thing God created was my nur (light).”
The oldest and noblest tribe in the whole of Arabia was Banu Hashim who were the descendants of Ibrahim through his son Isma'il. The Arabs respected and loved them for their honesty, knowledge and bravery.

The Birth: 
On 17th Rabi’ul-awwal, 570 AD a baby boy was born in the holy city of Mecca. Prophet Muhammad, son of Abdullah, grandson of Abdul-Muttalib, lost his father before he was born and when he was six, he lost his loving mother Aminah bint Wahb.

His grandfather, Abdul-Muttalib, took the responsibility of raising the orphan and at the age of ten, Prophet Muhammad lost  his grandfather. On his deathbed, he appointed his son Abu Talib as the guardian of Prophet Muhammad.
Gentle, soft spoken, tall and handsome boy, Prophet Muhammad, accompanied the trading caravans of Abu Talib, across the deserts, giving him deep insight into nature and man.
In his youth, Prophet Muhammad participated in Hilf (Confederation of) al-Fudul which demanded the help for the widows and orphans and protecting the oppressed.

The Prophet:
Lover of nature and quite, worried about human sufferings, Prophet Muhammad very often retired to Mount Hira' for meditations. One night, laylatul-qadr (the Night of Majesty) a voice addressing him, commanded "Recite in the Name of thy Lord." (Surah al-‘Alaq 96:1). Deeply excited by the strange phenomena of Divine Visitation, Prophet Muhammad hurried home to his wife, Khadijah, who listened to him attentively and said that "I bear witness that you are the Apostle of God."
After an interval, the voice from heaven spoke again "O thou shrouded in thy mantle, arise, and warn, and magnify thy Lord." (Surah al-Muddathir 74:1-3) This was a signal for him to start preaching the gospel of truth of One God.
In the beginning Prophet Muhammad invited only those near him, to accept the new Faith. The first to embrace Islam among women was Khadijah and among men `Ali. Soon after, Zayd ibn al-Harithah became a convert to the new Faith followed by Abu Bakr and `Uthman. `Umar hitherto a violent opponent of Islam, notorious for the persecution of the Muslims and a bitter enemy of the Prophet, embraced Islam, later.

Leadership:
For three long years, he labored quietly to wean his people from the worship of idols and drew only thirty followers. Prophet Muhammad now decided to appeal publicly to the Quraysh to give up idol worship and embrace Islam.
He invited forty of his kinsmen to a feast. At the gathering, Prophet Muhammad stated that he had lived a lifetime among them and asked if they had ever found him lying? The general response was "We have never found you lying, O al-Amin!" The Prophet of Islam asked if he were to tell them that their enemies had collected beyond the hills to attack them, would they believe? The reply was, "Yes." "Will you believe anything I will now say?" Again the reply was, "Yes." The Prophet addressed them: “I know no man in all Arabia, who can offer his kindreds, a more excellent thing than I now do. I offer you happiness both in this life and that which is to come. God Almighty has commanded me to call unto Him. Who, therefore, among you will assist me herein shall become my Brother and my Caliph?”
All of them hesitatingly declined the matter. Imam Ali (who was then given the title of "Amiru'1-Mu'minin" (the Commander of the faithful) by the Prophet, stood up and declared that he would assist the Prophet and vehemently threatened those who would oppose him. Prophet Muhammad with great demonstration of affection, embraced Imam Ali and declared to all, to hear and obey Imam Ali as his Deputy and Caliph. The gathering broke out into laughter, taunting Abu Talib that now he will have to obey his son.

Islam
Prophet Muhammad is the founder of the great religion of Islam, meaning submitting (oneself or one's person to Allah). The adherent of Islam is usually designated by the corresponding adjective Muslim. The Persians adopted a different adjective Musalman, from which are derived the Anglo-Indian Mussulman. But Muslims, certainly, dislike the terms Mohammedan and Mohammedanism, which seem to them to carry the implication of worship of Muhammad, as Christian and Christianity imply the worship of Christ.

The new Faith is simple, without complications, practical and useful for everyday life. It commands to believe and do good, keep up prayer and pay the poor rate. Two orders giving four principles of a successful way of life.
The new Creed had set in motion a terrific revolution, shaking the very foundations of the world. The vested interests, kings, priests, racketeers, and tyrants all were against, and they united to crush the movement of Islam.
The keepers of Ka'bah and owners of the idols, came to Abu Talib to stop his nephew from saying, "There is no god but Allah (la ilaha illa Allah)." The guardian uncle conveyed the request of the delegation to give Prophet Muhammad fortune larger than possessed by any, to make him a chief and even a king, if he agreed to give up his mission. Prophet Muhammad refused. Angry Arab chieftains threatened social boycott, destruction and death. Abu Talib (who actually became Muslim but did not announce his faith so that he may be able to defend the Prophet) promised to defend Prophet Muhammad.
Boys and louts of Mecca started pelting stones and abuses on Prophet Muhammad. Brave and loyal `Ali, son of Abu Talib, stopped this by his strong fists. The harassment and tortures, which the Prophet and his small band of faithful followers suffered at the hands of Quraysh were excruciating in the extreme. Some of the believers were dragged over burning sand, imprisoned, flogged and starved, but they firmly held to their Faith till death. Umayyah, master of Bilal, took Bilal to the desert and exposed him bare-back with his face, to the noon-day sun and placed a big stone on his chest and said, "There you shall remain, until thou art dead or thou hast adjured Islam." Dying with thirst in the heat he would only answer "Ahadun! Ahadun! (One [God]! One!)."
Almost ten years of hard work and preaching, in spite of all persecution, produced over a hundred followers. Physical cruelties and social boycott made life unbearable in Mecca. The Holy Prophet of Islam advised his followers to seek refuge in the neighbouring country of Ethiopia. Eighty-eight men and eighteen women sailed to the hospitable shores of the Negus, under the leadership of Ja'far at-Tayyar (brother of `Ali) and the cousin of the Holy Prophet. Arab chieftains pursued them and demanded their extradition.
Ja'far, pleading the cause of the refugees said to the king: O King! we were plunged in the depth of ignorance and barbarism; we worshipped idols, we lived in unchastity, we ate dead bodies and we spoke abominations; we disregarded every feeling of humanity and the duties of hospitality and neighbourhood; we knew no law, but of the strong (power), when God raised among us a man, of whose birth, truthfulness, honesty and purity we are aware; and he called us to the Unity of God and taught us not to associate anything with Him; he forbade us the worship of idols; and enjoined on us to speak the truth, to be faithful to our trusts, to be merciful and to regard the rights of neighbours; he forbade us to speak evil of women or to eat the sustenance of orphans; he ordered us to fly from vice and to abstain from evil; to offer prayers, to render alms, to observe the fast. We have believed in him, we have accepted his teachings and his injunction to worship God and not associate anything with Him. For this reason our people have risen against us, have persecuted us in order to make us forego the worship of God and return to the worship of idols of stone and wood and other abominations. They tortured and injured us, until finding no safety among them, we have come to thy country and hope wilt protect us from their oppression. The demand of the Quraysh were rejected and they returned to Mecca.
Several times the chieftains came to Abu Talib saying, "We respect your age and rank, but we have no further patience with your nephew. Stop him or we shall fight you."
Abu Talib asked Prophet Muhammad for his decision. With tears in his eyes the Apostle firmly replied, "O my uncle! if they place the sun on my right hand and the moon on my left, to force me to renounce my mission, I will not desist until God manifests His cause or I perish in the attempt."

Major Events during The Prophet Life:

Tragedies
In a period of troubles, trials and tribulations two major tragedies afflicted Prophet Muhammad. First the venerable guardian uncle Abu Talib died and shortly afterwards his noble wife Khadijah died, leaving behind her daughter Fatimah (peace be on her) - the only child she had from the Holy Prophet - the daughter who looked after her father so much so that the Prophet called her Umm Abiha (the mother of her father).

Muslim Era
With the death of Abu Talib, the Meccans planned to assassinate the Prophet. Under Divine guidance, he asked Imam Ali to sleep in his bed. As the murderers mistook Imam Ali for Prophet Muhammad, the Holy Prophet of Islam escaped. The Muslim era of Hijrah (Emigration) is named after this incident and dated from 17th Rabi’ul-awwal, 622 AD.
From the time he came to Medina, he was the grandest figure upon whom the light of history has ever shone. We shall now see him as, the king of men, the ruler of human hearts, chief law-giver and supreme judge. The Preacher who went without bread, was mightier than the mightiest sovereigns of the earth. No emperor with his tiaras was obeyed as this man in a cloak of his own clothing.
He laid the foundation of the Muslim commonwealth and drew up a charter which has been acknowledged as the work of highest statesmanship; a master-mind not only of his age, but of all ages.
Unlike the Arabs, the Prophet had never wielded a weapon, but now he was forced to defend Islam by force of arms. Commencing from the battle of Badr, a series of eighty battles had to be fought, which the infant community defended successfully.
One day Muhammad was sleeping under a tree, away from his camp. He was awakened by his enemy Du'thur ibn al-Harith with sword, standing over him. "O Muhammad! Who is there now to save you?" "God!" replied the Apostle. The wild Bedouin suddenly began to shiver and dropped his sword. The Prophet picked the sword and asked, "Who is there now to save you?" "Alas, no one!" "Then learn from me to be merciful." The Arab's heart was overcome and he embraced Islam.

Uhud 
A year later, Abu Sufyan, the famous long-lived enemy of Islam, again attacked the Muslims at Uhud. Hamzah, the first flag-bearer of Islam and uncle of the Prophet, was killed in action. In spite of strict instructions from the Prophet, a few Muslim soldiers deserted their positions when victory was in sight. This changed the course of the battle, when Khalid ibn al-Walid attacked the Prophet and the moment was saved by the arrival of Imam Ali. The enemies retreated and the issue was decided. Yet, the Prophet Muhammad was deeply grieved at the death of his uncle Hamzah.

Mubahilah 
In the 10th year AH, a Christian delegation from Najran came to the Prophet at Medina for religious discussions. Even after convincing arguments, the Christians refused to believe because they were not willing to give up their religion for the religion of Islam. 
According to Divine instructions in the Holy Qur'an: 
“And whoso disputes with thee concerning him, after the knowledge that has come to thee, say: ‘Come now, let us call our sons and your sons, our women and your women, ourselves and your selves, then let us humbly pray and so lay Allah's curse upon the ones who lie.’" (Surah al-Imran 3:61)
Muhammad suggested that next morning that the Christians should bring their women, sons and near ones and the Prophet would bring his, and they should pray, to invoke the curse of God on the liars, in order to end the argument.
At dawn Muhammad entered the field with his grandsons, leading Hasan by the hand, carrying Husayn in his arms, his beloved daughter Fatimah following him and Imam Ali walking behind her, with the banner of Islam. 
The Christians watching this procession from far, and came to the conclusion that Muhammad was the true Prophet of God, for he had brought with him his dearest and nearest ones. The Christians came to the Prophet and informed him that they were not willing to pray for the curse on the liars, instead they were willing to pay the jizyah (poll-tax or duties payable by non-Muslims in the realm of Islam) and to come to a settlement. The Prophet referred them to Imam Ali for terms.

Hudaybiyyah:
The Muslims had been in self-exile for six years and began to feel a keen yearning for their homeland, Mecca. The Prophet desired to perform a pilgrimage to Ka'bah. When he forsook his home town he was weak, but when he wanted to return, he was strong. He did not use his strength to force an entry into the sacred city. 
Finding the Quraysh hostile, Muhammad entered into a treaty known as the Peace of Hudaybiyyah, appearing not very advantageous to the Muslims, but which revealed the Islamic character of moderation and magnanimity. For the strong to exercise restraint and toleration is true courage. Having reached up to the door of their birth place with hearts over-flowing with impatient longing to enter it, the Muslims retraced their steps peacefully to Medina, under the terms of the treaty, which allowed them to perform the pilgrimage next year.

Khaybar:
The harassment and murders by the Jews, forced the Prophet into leading an army against Khaybar in the 7th year AH. The Muslims under the command of Umar turned back and were in despair. The Prophet said: "Tomorrow I shall assign the command of the Muslim force to a person who will be crowned by God with victory." The daybreak saw the Islamic banner waving gallantly in the hand of Imam Ali. 
The fateful battle began with Jewish champion warrior Marhab. With soul stirring shout of Allahu Akbar, the Dhulfiqar (sword) of Imam Ali descended on Marhab, piercing his skull. In the general encounter that followed, the Jews were defeated. The great victory of Islam was won and made Imam Ali the immortal conqueror of Khaybar.

Mecca: 
Towards the end of the year, Muhammad with his followers availed of the truce of Hudaybiyyah to accomplish the pilgrimage to Mecca. For three days, the Quraysh evacuated the city and watched the Muslims perform the pilgrimage. The strict observance of the terms of treaty, the self-restraint and regard for their pledged word displayed by the believers, created a great impression on the idolaters. Struck by Muhammad's kindness of heart and nobility of nature many Qurayshite chieftains adopted the Faith. 
In the 8th year AH, the idolaters violated the peace of Hudaybiyyah by attacking the Muslims. The enemies were defeated and Mecca was conquered. The Prophet who fled from Mecca as a fugitive, now returned home as a mighty conqueror. 
The Rahmatun lil'alamin (mercy unto all beings, i.e., the Prophet) entered the city with his head bowed low in thankfulness to the Almighty (Allah) and ordered a general amnesty, instead of the mass massacre of those who persecuted him and his followers.

King: 
Though a Prophet and a King, Muhammad was the man of the common people. He sat and ate with them. Shared their joys and sorrows, helped the weak, widows and orphans and sympathized with the distressed. He found the world sunk deep in degrading ignorance, superstition, vice and cruelty. He saw people disunited and engaged in perpetual wars, practising most revolting cruelties; daughters were buried alive and the widows of their fathers were inherited or sold by the eldest son. Among all this chaos, Muhammad established order and inspired in them the belief of One God; prohibited idolatry and made them think, not only of this world, but beyond the grave on a higher, purer and diviner plain, asking them to practise charity, goodness, justice, reasonableness and universal love. The whole mission was achieved in his lifetime.
The Five Purified Ones (Ahlul-Kisa')
Allah wills to keep away the uncleanliness from you, O People of the House! and purify you a (thorough) purification. (Surah Ahzab, 33:33) 
The Five Purified Ones - Muhammad, Ali, Fatimah, and their two sons Hasan and Husayn - became perfect examples of human conduct. They lived a life of extreme devotion, loyalty, utility, goodness, trust and charity, giving a standard of human values to every action of humanity. Their record of life is that of a work nobly and faithfully done, preaching the Unity of God, the equality of men and obliterating the tyranny of priests and rulers, breaking the shackles of wrangling creeds, oppressive rituals, and soul crushing dogmas; he broke down the barriers of caste, exclusive privileges and tyranny of vested interest. He proclaimed the importance of knowledge learning and hard work. 
Though the Holy Prophet was occupied in looking after the affairs of people, but he used to pay special attention to his family too. Some believers, requested him to allow them to buy lands and build houses for him. The reply was revealed by God: Say:
 "I do not ask of you any reward, but love for my relatives...; surely Allah is Forgiving, Grateful." (Surah ash-Shura 42:23) 
Thereupon, the believers asked the Prophet whose love was made incumbent on them? Muhammad answered "Love for `Ali, Fatimah, Hasan and Husayn."

Last Pilgrimage 
Under the Divine intuition of his approaching end, Muhammad prepared to make the farewell pilgrimage to Mecca. 
Before completing all the ceremonies of hajj, he addressed a huge multitude from the top of mount 'Arafat on 8th Dhi'l-hajjah, 11 AH in words which shall ever ring and live in the atmosphere: 
O people! Listen to my words, for I know not, if another year will be granted to me after this year, to find myself amongst you at this place. Your lives and property are sacred and inviolable to one another, until ye appear before the Lord, as this day and this month is sacred for all, and remember ye shall have to appear before your Lord, Who shall demand an account of all your actions. O ye people, ye have rights over your wives and your wives have rights over you... Treat your wives with kindness and love. Verily, ye have taken them on the security of God and made their persons lawful unto you by the Words of God. Keep faithful to the trust reposed in you and avoid sins. Usury is forbidden. The debtor shall return only the principal and the beginning will be made with the loan of my uncle Abbas son of `Abdul-Muttalib. Henceforth the vengeance of blood practised in the days of ignorance is prohibited; and all blood feuds abolished, commencing with the murder of Ibn Rabi`ah son of al-Harith son of Abdu1-Muttalib. And your slaves! see that ye feed them with such food as ye eat yourselves, and clothe them with the stuff ye wear; and if they commit a fault which ye are not inclined to forgive, then part from them, for they are the servants of the Lord and are not to be harshly treated. 
O ye people! listen to my words and understand the same, know all Muslims are brothers unto one another. Ye are one brotherhood, nothing which belongs to another is lawful unto his brother, unless freely given out of goodwill. Guard yourselves from committing injustice. Let him that is present tell it unto him that is absent. Haply he that shall be told may remember better than he who hath heard it.

Hadith of Ghadir 
Soon after finishing the hajj the Holy Prophet started for Medina. On his way, at 'Ghadir Khumm' the Voice from Heaven cried: 
“O Apostle! Deliver what has been revealed to you from your Lord; and if you do not, then you have not delivered His message and Allah will protect you from the people, surely Allah will not guide the unbelieving people." (Surah Maida 5:67)
 Muhammad immediately ordered Bilal to recall the Muslims, who had gone ahead, who were behind and who were proceeding to their homes at the junction, to assemble. The famous Sunni commentator, Fakhru'd-Din ar-Razi in his at-Tafsiru'l-kabir, (vol. 12, pp. 49 - 50), writes that the Prophet took Imam Ali by the hand and said: Whoever whose mawla (master), Ali is his master. O Allah! love him who loves Ali, and be the enemy of the enemy of Ali; aid him who aid `Ali, and forsake him who forsakes Ali. He (ar-Razi) writes further that Abu Bakr and `Umar congratulated Ali in the following words:
Congratulations, O son of Abu Talib! You became my mawla and mawla of every believing man and woman. 
Once again the voice from Heaven proclaimed: 
Today I have perfected your religion and completed My favor upon you and chosen for you Islam.