HDMI 2.1 is a version of the HDMI connection standard that increases the maximum bandwidth a cable and port can carry to up to 48 Gbit/s. This higher bandwidth is what makes features such as 4K video at 120 Hz, and in some cases 8K video, possible over a single HDMI connection.
Alongside raw bandwidth, HDMI 2.1 brought several gaming and audio features that many buyers care about just as much as the resolution increase, including VRR for smoother, tear free gaming, ALLM for automatic switching into Game Mode, and eARC for higher quality audio return to a soundbar or receiver.
Not every HDMI port labelled HDMI 2.1 on a television actually supports every one of these features at full bandwidth, since manufacturers can implement a subset of the specification, so checking a television's exact HDMI port specifications is worthwhile for anyone planning to use a modern games console. Our HDMI 2.1 explained guide and connections and setup page cover this in more detail.
