Rasta, or the Rastafari movement, is a religion and philosophy that accepts Haile Selassie I, the former Emperor of Ethiopia, as God incarnate, whom they call Jah. He is also seen as part of the Holy Trinity as the messiah promised in the Bible to return. The name Rastafari comes from Ras (Head or Duke or Chief) Tafari Makonnen, the pre-coronation name of Haile Selassie I.

The movement emerged in Jamaica among working-class and peasant black people in the early 1930s, arising from an interpretation of Biblical prophecy partly based on Selassie's status as the only African monarch of a fully independent state, and his titles of King of Kings, Lord of Lords, and Conquering Lion of Judah (Revelation 5:5). Other factors leading to its rise include the sacred use of cannabis, and various Afrocentric social and political aspirations, such as the teachings of Jamaican publicist and organiser Marcus Garvey (also often regarded as a prophet), whose political and cultural vision helped inspire a new world view. The movement is called Rastafarianism by some non-Rastas, although Rastas themselves generally regard that term as improper and offensive, because of the saying that "isms" denote "schisms".

The Rastafari movement has spread throughout much of the world, largely through interest generated by reggae music—most notably, that of Jamaican-born singer/songwriter Bob Marley. By 2000, there were more than one million Rastafari faithful worldwide. About five to ten percent of Jamaicans identify themselves as Rastafari. Many Rastafari follow an ital diet which essentially means living by the dietary Laws of Leviticus and Deuteronomy in the Old Testament.

It is not possible to explore the roots and development of the Rastafarian movement without detailing the life and times of Leonard Howell - who has been described as the "first Rasta". Howell formed a commune of up to 5000 persons at a place called Pinnacle, at St. Catherine in Jamaica. His exploits, trials and tribulations can still be understood as there are still people alive today, who were born and grew up at Pinnacle. It was the first commune of its type in Jamaica, and at its zenith was an oasis of peace and prosperity for those living there. Its destruction by the Colonial authorities, and the dispersal of its members, served only to sow the doctrine in more communities: the slums of Kingston - Back a Wall and the community of Waterloo and Tredegar Park in the parish of St. Catherine.