HLS (HTTP Live Streaming) is Apple's adaptive streaming protocol and, with DASH, one of the two dominant ways video and its audio reach players over the web. It describes the stream in playlist (.m3u8) files and delivers the media as a series of short segments fetched over ordinary HTTP, so it traverses CDNs and firewalls like any web content. Audio is declared with EXT-X-MEDIA tags that define rendition groups — the available languages, codecs, and channel layouts — which the player associates with the video and switches among per its own logic and the available bandwidth. HLS's reach across Apple devices made it ubiquitous, and its Low-Latency extension (LL-HLS) brings glass-to-glass delay down for live.
