You may know what HDMI is, but what does HDMI mean? HDMI stands for High Definition Multimedia Interface. It's a bit of a mouth full. However, this makes sense. The standard aims to provide high-resolution video and audio (or multimedia).
Of course, HDMI is often followed by a number – or the version number. Like many other standards, HDMI has been iterated upon over the years, and the higher the number, the more recent the version of HDMI.