Phonograph record

A phonograph record (also known as a gramophone record, especially in British English) or a vinyl record (for later varieties only) is a disc-shaped analog sound storage medium with an inscribed, modulated spiral groove. The groove usually starts near the outside edge and ends near the center of the disc. The stored sound information is made audible by playing the record on a phonograph (or "gramophone", "turntable", or "record player"). Records have been produced in different formats with playing times ranging from a few minutes to around 30 minutes per side. For about half a century, the discs were commonly made from shellac and these records typically ran at a rotational speed of 78 rpm, giving it the nickname "78s" ("seventy-eights"). "Vinyl" records made from polyvinyl chloride (PVC) were introduced in 1948, and by 1958 they became standard, replacing the old 78s and remain so to this day; they have since been produced in various sizes and speeds, most commonly 7 in (180 mm) discs played at 45 rpm (typically for singles, also called 45s ("forty-fives")), and 12 in (300 mm) discs played at 33+1⁄3 rpm (known as an LP's, "long-playing records", typically for full-length albums) – the latter is the most prevalent format today.