There are three main things you need to know about HDMI Cables. Firstly, HDMI stands for High Definition Multimedia Interface, and secondly what exactly does it do? It transmits digital video and audio signals to compatible devices through the use of one cable. Lastly, what are these compatibles devices? A HDMI Cable is used for connecting source devices, such as a DVD/Blu-Ray Player, Playstation and others, to a TV, monitor or even projector.