Muhammad Ali was an American professional boxer, activist, entertainer, poet, and philanthropist. Nicknamed The Greatest, he is widely regarded as one of the most significant and celebrated figures of the 20th century, and is frequently ranked as the best heavyweight boxer of all time.
Ali was born and raised in Louisville, Kentucky. He began training as an amateur boxer at age 12. At 18, he won a gold medal in the light heavyweight division at the 1960 Summer Olympics and turned professional later that year. He became a Muslim after 1961. He won the world heavyweight championship from Sonny Liston in a major upset on February 25, 1964, at age 22. On March 6, 1964, he announced that he no longer would be known as Cassius Clay but as Muhammad Ali. In 1966, Ali refused to be drafted into the military, citing his religious beliefs and ethical opposition to the Vietnam War. He was found guilty of draft evasion so he faced 5 years in prison and was stripped of his boxing titles.