HDMI is a digital interface for transferring HD video and audio. HDMI cables are used to connect an audio video device with an HDMI cable output to a TV, Monitor, Surround Sound Processor or projector with an HDMI input. The picture will look identical which ever HDMI cable you use, providing the cable is capable of transmitting the signal without too much loss. A cable with too much loss will be immediately obvious as the picture will look like it has white dots all over it, referred to as 'sparklies'.
HDMI cables used to be graded by the HDMI specification they had been tested to, for example HDMI 1.3 or HDMI 1.4, cables are now graded into categories, standard speed or high speed depending upon the data rate they can support. High Speed HDMI Cables can support higher resolutions beyond 1080p, eg 1440p and 2160p 4k x 2k as well as multichannel high definition audio. Most consumers now require a high speed HDMI cable to support features such as 3D over HDMI, however many older HDMI 1.1, 1.2 and 1.3 cables (especially shorter lengths) would be graded high speed had they been tested to the latest cable specifications. Some versions of high speed HDMI cables also support ethernet and audio return channel, these are now graded as High Speed with Ethernet HDMI Cables, use this cable if you plan to connect web-enabled devices or plan to use return audio, starting from just a few pounds this is our recommended cable if you are looking for a future proof cable as they are fully backwards compatible.
If you came here looking to buy an HDMI 2.0 Cable then select high speed with ethernet, the term HDMI 2.0 is not applicable to cables.
Tablet computers and smaller devices often use Mini HDMI Cables or Micro HDMI Cables, these are smaller versions of the HDMI connector. Some Tablets and smartphones can transfer HDMI via their micro USB connector using an MHL Adapter, the device must support MHL for these to work.
If you want connect your HDMI source such as Sky HD or Virgin Media HD to two or more TVs then you will need an HDMI Splitter, these duplicate the HDMI signal allowing it to be displayed on multiple screens.
If you have more HDMI devices than your HDMI inputs on your TV then you can use an HDMI Switch to expand the number of inputs.
Its possible to send HDMI over longer distances using an HDMI over CAT5 Extender, these allow HDMI to be transferred over cheap CAT5 or CAT6 network cables up to 120 metres.
HDMI can be adapted to different digital connector types quite easily using an HDMI Adapter, converting to analogue signal formats such as VGA is also possible using an HDMI to VGA Converter.