LL-HLS (Low-Latency HLS) is Apple's extension to HLS that cuts the glass-to-glass delay of live streams from the old 20-30 seconds toward 2-5 seconds, closing much of the gap with broadcast. It does this chiefly with partial segments — publishing small parts of a media segment as they're produced rather than waiting for the whole thing — plus blocking playlist reloads that let the player request the next part and have the server hold the response until it's ready, removing polling delay. Audio rides along in the same low-latency segments. LL-HLS competes with low-latency DASH and CMAF-LL; all of them trade a little buffering safety margin for much lower latency in live sports, auctions, and interactive streams.
