HEVC (High Efficiency Video Coding, H.265) succeeds H.264 with roughly 40-50% better compression at the same quality, which makes it the default for bandwidth-heavy formats like 4K and HDR. It has broad hardware decode support on modern phones, TVs, and set-top boxes, especially in the living room.
Its adoption was slowed by a fragmented, expensive patent-licensing landscape (multiple pools), which is precisely what motivated the royalty-free AV1. In practice HEVC is the workhorse for premium UHD/HDR delivery to capable devices, while H.264 covers the long tail and AV1 is added where it is supported.
