Compact disc
Compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony and released in 1982. The format was originally developed to store and play only sound recordings (CD-DA) but was later adapted for storage of data (CD-ROM). Several other formats were further derived from these, including write-once audio and data storage (CD-R), rewritable media (CD-RW), Video Compact Disc (VCD), Super Video Compact Disc (SVCD), Photo CD, PictureCD, CD-i, and Enhanced Music CD. The first commercially available audio CD player, the Sony CDP-101, was released October 1982 in Japan.
CD player
A 2005 book stated that after Apple Computers entered the music industry, within ten years it became the dominant seller of portable digital audio music players (its iPod line), "...while former giant Sony (maker of the [portable] Walkman and [CD] Discman [was] struggling." This market change was initiated in 1998, when the first portable digital audio player, the Rio personal digital music player, was introduced. Portable MP3 players like the Rio competed with portable CD players. The 64 MB version of the Rio MP3 player enabled users to store about 20 songs on the player. One of the benefits of the Rio over portable CD players was that since the Rio had no moving parts, it offered skip-free playback. Since 1998, the price of portable digital audio players has dropped and the storage capacity has increased significantly. In the 2000s, users can "carry [their] entire music collection in a [digital audio] player the size of a cigarette package." The 4 GB iPod, for example, holds over 1,000 songs.