This refers to the video codec (HEVC - High Efficiency Video Coding). A raw 4K HDR stream is massive—it would require terabytes of storage for a single season. The "x265" codec is a modern compression standard that reduces the file size significantly while retaining near-lossless quality. It is more efficient than its predecessor, x264. For the viewer, this means you are getting 4K quality without needing a server farm to store the files. It allows for smoother playback on modern hardware while maintaining the bitrate necessary to prevent "banding" in the show’s many colorful, gradient-heavy scenes.
, which is downloaded directly from the server without re-encoding. : Short for High Dynamic Range Squid Game S01 2160p NF WEBRip HDR X265 DD 5.1