Initially, the band pioneered the musical genre of folk rock on their album Mr. Tambourine Man (1965), by melding the influence of the Beatles and other British Invasion bands with contemporary and traditional folk music. As the 1960s progressed, the band was influential in originating psychedelic rock and raga rock, with their song "Eight Miles High" and the albums Fifth Dimension (1966), Younger Than Yesterday (1967) and The Notorious Byrd Brothers (1968). They also played a pioneering role in the development of country rock, with the 1968 album Sweetheart of the Rodeo representing their fullest immersion into the genre.
The original five-piece lineup of the Byrds consisted of Jim McGuinn (lead guitar, vocals), Gene Clark (tambourine, vocals), David Crosby (rhythm guitar, vocals), Chris Hillman (bass guitar, vocals), and Michael Clarke (drums). However, this version of the band was relatively short-lived and by early 1966, Clark had left due to problems associated with anxiety and his increasing isolation within the group. The Byrds continued as a quartet until late 1967, when Crosby and Clarke also departed the band. McGuinn and Hillman decided to recruit new members, including country rock pioneer Gram Parsons, but by late 1968, Hillman and Parsons had also exited the band. McGuinn elected to rebuild the band's membership and, between 1968 and 1973, he helmed a new incarnation of the Byrds, featuring guitarist Clarence White among others. McGuinn disbanded the then current lineup in early 1973, to make way for a reunion of the original quintet. The Byrds' final album was released in March 1973, with the reunited group disbanding soon afterwards.
Several former members of the band went on to successful careers of their own, either as solo artists or as members of such groups as Crosby, Stills, Nash & Young, the Flying Burrito Brothers and the Desert Rose Band. In the late 1980s, Gene and Michael both began touring as the Byrds, prompting a legal challenge from McGuinn, Crosby, and Hillman over the rights to the band's name. As a result of this, McGuinn, Crosby, and Hillman performed a series of reunion concerts as the Byrds in 1989 and 1990, and also recorded four new Byrds' songs. In 1991, the Byrds were inducted into the Rock and Roll Hall of Fame, an occasion that saw the five original members performing together for the last time. Gene Clark died of a heart attack later that year, while Michael Clarke died of liver failure in 1993. McGuinn, Crosby, and Hillman remain active.
The nucleus of the Byrds formed in early 1964, when Jim McGuinn, Gene Clark, and David Crosby came together as a trio. All three musicians had a background rooted in folk music, with each one having worked as a folk singer on the acoustic coffeehouse circuit during the early 1960s. In addition, they had all served time, independently of each other, as sidemen in various "collegiate folk" groups: McGuinn with the Limeliters and the Chad Mitchell Trio, Clark with the New Christy Minstrels, and Crosby with Les Baxter's Balladeers. McGuinn had also spent time as a professional songwriter at the Brill Building in New York City, under the tutelage of Bobby Darin. By early 1964, McGuinn had become enamored with the music of the Beatles, and had begun to intersperse his solo folk repertoire with acoustic versions of Beatles' songs. While performing at The Troubadour folk club in Los Angeles, McGuinn was approached by fellow Beatles fan Gene Clark, and the pair soon formed a Peter and Gordon-style duo, playing Beatles' covers, Beatlesque renditions of traditional folk songs, and some self-penned material. Soon after, David Crosby introduced himself to the duo at The Troubadour and began harmonizing with them on some of their songs. Impressed by the blend of their voices, the three musicians formed a trio and named themselves the Jet Set, a moniker inspired by McGuinn's love of aeronautics.