Laserdisc, LD, or video disc was the first optical disc storage media, and an industry-wide term for consumer laser video. During its life, the format has also been known as LV (for LaserVision, actually a player brand by Philips). The players are also sometimes referred to as VDPs (Video Disc Players).
LD was invented by Philips beginning in the late 1960s and first demonstrated by Philips and MCA in 1972, and was available on the market in 1978, or about as long as the VCR and six years longer than CD. There are more than 1 million players in home use in the US (compared to 85 million VCRs), and more than 4 million in Japan (ten percent of households there). LD has been largely replaced by DVD.
LD had a number of advantages over VHS. It featured a far sharper picture and level of sound quality, with the ability to deliver multiple audio channels, both analog and digital. This allowed "special editions" of movies with extras like director commentaries to be released. Access was random, meaning that one could go to any point on the disc very quickly (depending on the player and the disc, within a few seconds at the most). This instant seeking allowed a new breed of laserdisc-based video arcade games, beginning with Dragon's Lair, to be born. As the LDs are read optically instead of magnetically, a properly-manufactured LD will theoretically last beyond one's lifetime, and as the discs had no moving parts, they were cheaper to manufacture.
The format was not without its disadvantages. The discs were 12 inches across, and were both fragile and heavy. There was no way for home user to record to an LD. Depending on the format, each side of an LD could hold 30-60 minutes worth of footage, and then a disc flip would be required. Most players did this automatically, but except in high-end models with a pre-read buffer, this was accompanied with a pause in the movie of around 10 seconds, and if the movie was longer then two hours, it eventually required putting in a second disc. Many early laserdiscs were not manufactured properly, causing the metallic part of the discs to oxidize, eventually destroying the disc in a process known as "laser-rot" (early CDs suffered similar problems).
The format was not well-accepted outside of videophile circles in North America, but became more popular in Japan. Part of the reason was marketing. In North America the cost of the players and discs were kept far higher than VHS to make up for lack of demand. In Japan, LD was marketed like DVD (LD's replacement) was on its release - prices were kept low to ensure adoption, so in Japan an LD and a VHS tape were often identically priced. LD quickly became the dominant format-of-choice amongst Japanese collectors of anime, helping drive it acceptance.
The compact disc for audio was based on the laser disc technology. One reason for the (mostly) failure of laser discs may have been that it was not possible to record them, and the competing video cassette recorder devices could record using tape cassettes. When they were first introduced, laser discs were believed to be disruptive technology, a promise they failed to fulfil. Compact discs and DVDs were to be disruptive instead.
Although LDs and their players are no longer manufactured, LDs are now considered by many to be collectors' items. Some videophiles regard them as far superior to any other video playback system except for, perhaps, DVD.