What is an HDMI used for?
HDMI stands for High-Definition Multimedia Interface, a standard for simultaneously transmitting digital video and audio from a source, such as a computer or TV cable box, to a computer monitor, TV or projector.
What is ARC used for?
One of the best and yet least-understood HDMI features is ARC, or Audio Return Channel. It's a feature that enables you to simplify your system and is compatible with most TVs, receivers and soundbars. In its most basic form, ARC uses an HDMI cable to send audio from a TV back to a receiver or soundbar.