The HDMI interface is electrically identical and compatible with the video-only DVI interface, which came first. For example, if a cable box or PC has DVI out, but the TV or monitor only has HDMI ...
It was more convenient than DVI or ... loose. HDMI cables are all meant to be Type-A to Type-A, with adapters used to change the plug on the end between types. Cables with different plugs on ...