A Super Audio CD is a read-only optical disc for storing audio. This type of CD was introduced in 1999. Sony and Philips Electronics worked together to develop it. It was intended for the SACD to be the main successor to the original CD. You may not be able to tell a real difference between SACDs and CDs at normal volume levels, but the SACD does offer more channels such as surround sound, and other exclusive features like extended playback time.
There are 3 different types of SACDs. Hybrid, which are encoded with a 4.7 GB HD (DSD) layer as well as a PCM (Redbook) audio layer, Single-Layer, which are DVD-5 encoded with a 4.7 GB HD layer as well, and Dual-Layer, a DVD-9 encoded with 2 HD 8.5 GB layers.
The SACD never became popular, since they required a special player and would cost 2x-6x as much as a CD. CDs however, had booming sales throughout the 1990s.
By 2009, there had been more than 6,000 SACD releases, more than half being jazz or classical music. Many popular artists have released almost all of their older music on SACDs, such as Pink Floyd, The Who, and Roxy Music. Other artists have released their newer music on SACD, such as bands Sting, and Genesis.
Many labels, artists, and companies used SACDs for a little while, especially orchestras. Some labels have even been created by orchestras to provide full support for these high resolution SACDs. Why? Because SACDs include five full-range plus LFE-multi-channel (surround sound) and stereo (dual-channel) mixes, which are essential for beautiful, perfect sound!