The Buddha was a prince named Siddhattha Gotama. He was born in the sixth century BCE at Lumbini, in what is now Nepal.
Early life
His father was King Suddhodana and his mother Queen Maya, who died shortly after Siddhattha was born. His maternal aunt, Mahapajapati Gotami, raised him, becoming in effect his adoptive mother. She would later become the first bhikkhunī — the first Buddhist nun — and head the order of nuns.
Prince Siddhattha married at sixteen, to a princess named Yasodhara. She was in fact his cousin, which was common enough at the time, particularly within royal families.
His life was privileged and full of luxury, and deliberately sheltered from the harder realities outside the palace.
The four sights
Eventually the young Siddhattha saw what Buddhists call the four sights, and through them came to recognize the unsatisfactory nature of our perishable, conditioned existence. He saw a sick man, an old man, a corpse, and a monk.
These made a deep impression on him. At twenty-nine, shortly after the birth of his only son, Rahula, he decided to leave his kingdom and become an ascetic in search of a solution to suffering.
Six years of searching
For six years the ascetic Siddhattha wandered the Ganges valley, meeting the well-known religious teachers of the day, studying and following their systems and methods, and submitting himself to severe ascetic practices.
None of it satisfied him. So he left the traditional religions and their methods behind and followed his own path — the middle way, between the extremes of sensual indulgence and self-mortification.
The awakening
It was then, beneath the Bodhi tree on the bank of the Neranjara river, at the age of thirty-five, that Siddhattha reached awakening. After it he would be known as the Buddha: the one who woke up.
He knew it would be difficult for a world full of craving, lust and hatred to understand what he had found. That produced some hesitation at first. But the Buddha decided to teach, and to pass on his Dhamma.
Forty-five years of teaching
His first sermon was given to a group of five ascetics — his former companions — in the deer park near Benares. His first teachings were the Four Noble Truths and the Eightfold Path, both of which remain essential parts of Buddhism today.
The Buddha taught for forty-five years. Well ahead of his time, he taught every class of men and women, without any distinction of caste, gender or social standing.
He died at the age of eighty at Kusinara.
Buddhism today
Buddhism is now found in Thailand, Myanmar, Sri Lanka, Bhutan, Laos, Japan, China and Vietnam, among others. There are an estimated 500 million Buddhists in the world.
If you want to go further, the next question is usually which tradition you are looking at — Theravada and Mahayana take his teaching in noticeably different directions.