The HDMI interface is the uncompressed, all-digital, global connectivity standard that delivers true HD quality for consumer electronics and PC products via a single cable.

HDMI technology was specifically designed to meet the needs of today’s – and tomorrow’s – HD entertainment systems. It transmits digital video, multi-channel surround sound, and advanced control data through a single cable, replacing up to eleven older cables with a single connection. Its simplicity is matched only by its extraordinary performance. High-bandwidth, all-digital, and never compressed, HDMI provides the highest possible signal quality.

More than 800 manufacturers have adopted the HDMI standard since 2003. With 229 million HDMI-enabled devices shipping in 2008, and 300 million more projected in 2009, analysts expect to see over a billion HDMI devices in the market by 2010, when every new digital TV will feature at least one HDMI port. HDMI connectivity is already standard on a wide range of products, from HDTVs and Blu-ray Disc players to multimedia PCs, gaming systems, digital camcorders, and more.

Compatibility with DVI

A DVI signal is electrically compatible with an HDMI video signal; no signal conversion needs to take place when an adapter is used, and consequently no loss in video quality occurs. As such HDMI is backward compatible with Digital Visual Interface digital video (DVI-D or DVI-I, but not DVI-A) as used on modern computer monitors and graphics cards. This means that a DVI-D source can drive an HDMI monitor, or vice versa, by means of a suitable adapter or cable. However, the audio and remote-control features of HDMI will not be available. Additionally, not all devices with DVI input support High-bandwidth Digital Content Protection (HDCP). Without such support by the device, an HDCP-enabled signal source will suppress output and so prevent the device from receiving HDCP-protected content.

HDCP

HDMI can use HDCP to encrypt the signal if required by the source device. CSS, CPPM, and AACS requires the use of HDCP on HDMI when playing back encrypted DVD-Video, DVD-Audio, and Blu-ray Disc. The HDCP Repeater bit controls the authentication and switching/distribution of an HDMI signal. According to HDCP Specification 1.2 beginning with HDMI CTS 1.3a, any system which implements HDCP must do so in a fully-compliant manner. HDCP testing which was previously only a requirement for optional tests such as the "Simplay HD" testing program is now part of the requirements for HDMI compliance. HDCP allows for up to 127 devices to be connected together with up to 7 levels using a combination of sources, sinks, and repeaters. A simple example of this is several HDMI devices connected to an HDMI AV receiver that is connected to an HDMI display.

There are devices called HDCP strippers which can remove the HDCP information from the video signal and allows the video to be playable on non-HDCP compliant displays. An example of an HDCP stripper for HDMI is the HDfury2 which can convert the video to VGA or component video and the audio to stereo analog or digital TOSLINK.