High definition or HD may refer to:

• Blu-ray Disc, the universal optical High Definition disc format
• HD Photo, former name for the JPEG XR image file format
• HDV, format for recording high-definition video onto magnetic tape
• HiDef, 24 frames-per-second digital video format
• High-Definition Multimedia Interface (HDMI), all-digital audio/video interface capable of transmitting uncompressed streams
• High-definition television (HDTV), television signals and apparatus with higher resolution than their contemporary counterparts
  • Ultra-high-definition television, a further step in television resolution, but not a successor.
• High-definition video, used in HD broadcasting, digital film, computer HD video file formats, and video games

• Dolby TrueHD, lossless audio compression codec
• DTS-HD Master Audio, lossless audio compression codec
• High Definition Compatible Digital, discontinued digital audio optical disc format
• High-definition audio, general marketing term for high fidelity audio products and services
• Intel High Definition Audio, 2004 Intel specification for hardware and associated drivers for Personal computer audio
• Wideband audio, also known as HD voice, is high definition voice quality for telephony audio

• "Hi-Definition", 2008 single from Lupe Fiasco's The Cool
• High Definition (Joe Morris album), 2008
• High Definition (Shootyz Groove album), 1999
• "High Definition", a single from Waterparks' 2019 album, Fandom

• High Definition (radio program), 2006 Canadian radio program
• High-definition map, used in autonomous driving