LPs are usually discs, either 10 or 12 inches in diameter, made from a vinyl material and weigh between 160 and 200 g. Some manufacturers experimented with lighter weight material, creating discs as light as 90 g, but these lighter discs were prone to damage. The grooves, which hold the musical data, start on the outside of the disc and spiral inward, lasting about 22 minutes per side.
While 22 minutes per side is the standard, extended play records have been pressed at 26 minutes per side. While this may seem short to those used to CDs or an endless supply of MP3s, the previous standard of the 78 RPM lasted just 4 minutes per side, so the long play record was a well-named replacement.
The long play record was first introduced by Columbia Records in 1948, unveiled at the Waldorf Astoria during a dramatic press conference. The LP quickly replaced the shorter running 78 and became the leader in music technology. The LP was never able to be reliably played in a moving vehicle, however, making it unusable for a car, and its large size kept it from portability in general. The tape, while portable and usable in a car, never replaced the LP as a standard due to the higher sound quality of the LP.
In the 1980s the CD came onto the stage and by 1991 had displaced the LP as the music format leader. There are still many aficionados who swear by LP sound quality. For these music lovers, LPs are still being pressed in small quantities and some music stores specialize mainly in used LPs.
With 1600 feet of grooves the LP can play for about 22 minutes per side. These grooves are recorded by taking the sound and piping it to a cutting stylus, which vibrates as it cuts. This vibration is able to be played back as an audio recording. As technology improved in both the recording devices and the recording medium, the records become both more durable and better in sound quality.
Other formats have existed for disc records, including the original 78 and the 45, which played a single song, up to about 8 minutes per side on a 7-inch disc. Early formats were not set at a standard speed and could be between 60 and 120 RPM. Discs have also been pressed with speeds as low as 16 RPM.