The term, "oldies," refers to both popular music from the 1950s-1970s and the radio format that specializes in this type of music. "Golden oldies" usually refers to oldies music exclusively from the 1950s-early 1960s. Oldies songs are typically from the R&B, pop and rock music genres but may also include country, movie soundtrack, novelty, and other types of popular music played on the radio from around 1950-on. Pop music genres that had their heyday before the 1950s (e.g., ragtime, big band) are generally considered "too old" to be included in the oldies radio format. Oldies music radio stations, which typically feature bands and artists such as (to name a few) Elvis Presley, Bill Haley, Little Richard, Pat Boone, Sam Cooke, the Beatles, the Beach Boys, the Rolling Stones, the Rascals, the Association, the Temptations, the Who, Elton John, and Fleetwood Mac, cover a wide variety of styles including early rock and roll, rockabilly, doo-wop, surf rock, girl groups, the British Invasion, folk rock, psychedelic rock, baroque pop, soul music, Motown, and bubblegum pop. Oldies music also overlaps with classic rock which focuses on the rock music of the late 1960s and 1970s as well as newer music in a similar style.

The phrase, "oldies but goodies," was first coined in 1957 by renowned deejay Art Laboe who, at around that time, used to get frequent requests from his listeners for songs from the early 1950s. A central figure in L.A. radio for over half a century, Laboe was the first deejay to play rock n roll on the West Coast and one of the first to play black and white artists on the same show. In 1959, he put together the first LP to feature (mostly older) songs by different artists. This immensely popular compilation album, entitled "Oldies But Goodies," stayed on Billboard's Top 100 LP's chart for over three years and has, to date, spawned some 14 sequels.

Soon after the release of Laboe’s first "Oldies But Goodies" album, the phrase, "oldies but goodies," became commonplace and by around 1960, people were waxing nostalgic for 1950s doo-wop which was already starting to be classified as "oldies." Little Caesar And The Romans’ 1961 hit, "Those Oldies But Goodies (Remind Me of You)" and its sequel, "Memories of Those Oldies But Goodies," both pay homage to early doo-wop and doo-wop artists. This wave of nostalgia brought about a doo-wop revival in the early 1960s which was the first of many nostalgia movements in pop music since the term, "oldies," was first applied to older pop music.

While "golden oldies" has remained a constant over the years, the larger body of pop music that we still call "oldies" today - which is made up of core golden oldies songs plus more modern material - is not fixed but has been gradually expanding forward in time to keep up with changing demographics. Nowadays, oldies music is generally considered to include all of the 1970s, even disco, and the same is expected to be true someday for the music of the 1980s, now often described as "retro." Oldies music is also expanding in breadth as thousands of long-forgotten tunes from the 1950s and 1960s that never made the Top 40 in their day are being rediscovered and resurrected. Whether because of nostalgia, curiosity, or a genuine love for good music, the oldies format has maintained a huge following and will probably continue to do so for many years to come.