Hard disk image file used by Microsoft Windows Virtual PC; stores data within a single file that acts as an individual hard disk; may be used to install multiple operating systems on a single computer, test software programs, or run older applications.

The VHD Image Format Specification has been available as a royalty-free license since June, 2005.

Source file written in VHDL, which stands for Very High Speed Integrated Circuits (VHSIC) Hardware Description Language (HDL); often used for automating the design of electrical circuits and components.

Electronic engineers can use VHDL to describe hardware components in a text-based format. This description can then be used to manufacture a physical circuit such as a motherboard, processor, or memory module.