A single is a music release focused on one primary track, often accompanied by a B-side. In physical media, singles are most commonly pressed as 7-inch vinyl records playing at 45 RPM, though 12-inch singles (especially in dance and electronic music) also exist. CD singles (CD-S) were popular in the 1990s and early 2000s.
The single has been the backbone of the music industry since the dawn of recorded sound. Before albums existed, singles were the primary way people bought music. The 7-inch 45 RPM format, introduced by RCA Victor in 1949, became the dominant single format for decades. Jukebox culture was built entirely around 45s.
For collectors, singles are treasure troves. Original 45s from the 1950s-1970s can be incredibly valuable, and many songs were released as singles but never appeared on albums. Promo singles, picture sleeve editions, and colored vinyl variants are highly collectible. Modern artists still release limited vinyl singles for Record Store Day and special occasions.
The best-selling physical single of all time is Bing Crosby's "White Christmas" (1942), with estimated sales exceeding 50 million copies worldwide.