When The Byrds first started out in 1965, they took the sounds of the British invasion and combined it with American folk music made popular by Bob Dylan and others. Their sound was tailored strongly by the jangly tone of Roger McGuinn’s 12-string Rickenbacker which became a strong influence a decade later for Tom Petty and the Heartbreakers. They were also known for their distinct vocal harmonies.
The Byrds would later add Eastern world, psychedelic, and country music influences to their sound. These changes caused creative differences within the band leading to David Crosby eventually leaving the group and forming Crosby, Stills, Nash (and Young). Numerous other lineup changes would happen down the line, with Roger McGuinn remaining the only consistent member. They eventually disbanded in 1973.