Blog

Mar 10, 2023

What is compact disc (CD)?

A compact disc is a portable storage medium that can record, store and play back

A compact disc is a portable storage medium that can record, store and play back audio, video and other data in digital form.

A standard compact disc measures 4.7 inches, or 120 millimeters (mm), across, is 1.2 mm thick, weighs between 15 grams and 20 grams, and has a capacity of 80 minutes of audio, or 650 megabytes (MB) to 700 MB of data.

A CD works by focusing a 780 nanometer wavelength semiconductor laser onto a single track of the disc. As the disc rotates, the laser beam measures differences in the way light is reflected off the polycarbonate layer on the bottom of the disc, converting it to sound.

CDs are fragile and prone to scratches; they can be repaired, but disc readability may be affected.

James Russell, an American inventor, envisioned an alternative to vinyl albums to store and play audio recordings. He was the first person to file a patent for a product resembling a combination of laser, digital recording and optical disc technologies in 1966. Philips Electronics and Sony Corp. then purchased licenses of the technology in the 1980s.

The first commercial compact disc, a recording of a series of Chopin waltzes performed by pianist Claudio Arrau, was released in 1982. Prior to that, test recordings were completed in 1979. In 1981, the BBC demonstrated a CD playing the Bee Gees' album, Living Eyes.

The first CD player, the CDP-101, was released commercially in 1982, and listeners began to use the format across the globe. Early compact discs were made at just two factories, owned by Philips and Sony.

Before the process became streamlined, individual discs cost $30, but as manufacturers proliferated, prices dropped. Hitachi also released a CD player in 1982, but the majority of sales belonged to Sony, with 20,000 sold in the first year.

CDs joined tape cartridges in generally replacing the phonograph record for playing music. Initially, CDs were read-only, but later technology allowed users to record on them, as well. As the 1980s came to an end, compact discs became the industry standard for audio recordings.

With the rise of personal computers (PCs) and other commercial technologies, various compact disc formats branched off to store data. Sony and Philips created specifications for these CD versions -- called Rainbow Books, due to the various colors on the book bindings -- to define each product format. The Red Book outlined the specifications for a standard CD.

Compact disc variations include:

The CD has seen a steady decline in use, particularly during the early 2010s.

Digital formats have overtaken CDs in the music world, which has seen a huge shift away from physical mediums with the rise of streaming audio and digital downloads. While compact disc sales were more profitable for those in the music industry, convenience and low costs have fewer consumers turning to the physical medium.

When compact discs were initially on the rise, PCs could only store approximately 10 MB of data, which had many turning to the CD for storage. That is no longer the case. With higher capacity hard drives and online storage options consistently entering the market, compact discs and tape cartridges are no longer the top choice for many consumers.

In 1995, Panasonic, Philips, Sony and Toshiba created the DVD format as a possible media replacement for compact discs. A DVD has the same dimensions as a CD, but a much higher storage capacity of 4.7 gigabytes (GB). The format is probably most known for video entertainment storage, but is also used for software and other digital data. DVDs can be played on a DVD player, as well as in a DVD-ROM in a computer.

In 2003, Blu-ray was introduced as a replacement for DVD. Blu-ray has a capacity of 25 GB, which allows for higher quality video and audio with higher resolution.

Editor's note: This article was revised in 2023 by TechTarget editors to improve the reader experience.