High Definition Compatible Digital (HDCD) is a proprietary audio encode-decode process that claims to provide increased dynamic range over that of standard Compact Disc Digital Audio, while retaining backward compatibility with existing compact disc players.

Originally developed by Pacific Microsonics, the first HDCD-enabled CD was released in 1995. In 2000, the technology was purchased by Microsoft, and the following year, there were over 5,000 HDCD titles available. Microsoft's HDCD official website was discontinued in 2005; by 2008, the number of available titles had declined to around 4,000.

A number of CD and DVD players include HDCD decoding, and versions 9 and above of Microsoft's Windows Media Player on personal computers are capable of decoding HDCD.

HDCD was a favorite for several artists such as Neil Young, the Beach Boys and the Grateful Dead, all of whom have had multiple titles in their catalogs reissued in this format.