Leonardo was born on 15 April 1452, in the Tuscan hill town of Vinci, in the valley of the Arno River. His grandfather, Antonio da Vinci, wrote down the details of the birth. Leonardo's parents were not married. His father was a Notary, Ser Piero da Vinci. His mother, Caterina, was a servant. She may have been a slave from the Middle East. or from China.His father later on took custody of Leonardo and his mother remarried and had 5 more children. Leonardo's full name was "Leonardo di ser Piero da Vinci", which means "Leonardo, the son of Messer (Mister) Piero da Vinci".

Leonardo spent his first five years living in a farm house with his mother. Then he lived at Vinci with his father, his father's new wife Albiera, his grandparents and uncle, Francesco.When Leonardo grew up, he only wrote down two memories from his childhood. He remembered that when he was lying outside in his cradle a large bird flew from the sky and hovered over him. Its tail feathers brushed his face. Leonardo's other important memory was how he found a cave while exploring in the mountains. He was terrified that some great monster might be hiding there. But he was also very excited and wanted to find out what was inside.

Leonardo started painting while he was still a boy. Giorgio Vasari wrote about Leonardo's life shortly after his death. He tells many interesting stories about how clever Leonardo was. He says that Leonardo painted a round wooden shield with a picture of snakes spitting fire. Messer Piero took his son's painting to Florence and sold it to an art dealer.