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Glossary · protocol

What is HLS (HTTP Live Streaming)?

HLS (HTTP Live Streaming) is a streaming protocol developed by Apple. The video is split into short chunks (~6-10 seconds), each delivered over plain HTTPS. A manifest file (.m3u8) lists the chunks. Used by Apple TV, YouTube live, Twitch alternates, and most major streaming services.

Also called:http live streaming · m3u8 · apple hls

HLS solves a key streaming problem: how do you deliver live video over the same CDN infrastructure that serves static files? By chunking the stream into short, individually-cacheable segments. Each segment is a normal HTTPS file fetch; CDNs handle them like any other download.

For VOD (recorded video), HLS still divides the video into segments, but the manifest lists them all upfront. Players can start playback before the full manifest is fetched and adapt quality between segments without re-buffering.

YouTube uses DASH (a similar protocol) for its main delivery, and HLS for live content and some mobile flows. Both are technically interchangeable from a viewer's perspective.

Common questions

How is HLS different from DASH?
They solve the same problem with different conventions. HLS uses .m3u8 manifests and TS (or fMP4) segments; DASH uses .mpd manifests and fMP4 segments. Modern players support both; the choice is mostly about which CDN tooling you already have.

Related terms

DASH (MPEG-DASH)

DASH (Dynamic Adaptive Streaming over HTTP) is an open streaming protocol.

Fragmented MP4

Fragmented MP4 (fMP4) is an MP4 variant where the file is split into many short chunks ("fragments"), each containing its own header.

Manifest (streaming)

A manifest is a small text file that lists every segment of a streaming video, plus available qualities, codecs, and timing.

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