LPs are long-playing records made of vinyl, 10 or 12 inches in diameter. Originally, LPs could hold around 22 minutes of music per side, but certain recording techniques increasec that number. With the advent of compact discs and digital music, LPs have become a niche product for music collectors.
Traditionally, a LP contains a single spiral groove on each side, beginning at the outer edge of the record and spiraling in towards the center. When the record needle is placed on the outermost edge, it finds this groove and follows it inward as the record spins on the turntable. Some recordings contain multiple grooves, allowing multiple musical programs to be recorded on the same album and providing a different experience depending on where the needle is placed.
The sound on an LP record is produced as the phonograph needle moves through the groove, picking up vibrations from the surface. This analog method of sound production produces signature pops and crackles, especially when playing older records that have suffered wear. Many enthusiasts also call the sound of vinyl more "warm" than digital music and enjoy these subtle distortions as part of the listening experience. The fact that the act of listening to a disc causes wear on the recording medium helps to establish LPs as collectors' items, as the number of pristine copies of any given pressing decreases over time.