The M3U8 file format is a plain text playlist file used by Apple's HTTP Live Streaming (HLS) adaptive bitrate streaming protocol. It contains metadata describing the location of the various multimedia files (audio and video segments) that make up the stream. These files are typically encoded at different bitrates, allowing the player to dynamically switch between them based on network conditions, ensuring smooth playback even with fluctuating bandwidth. The M3U8 file itself doesn't contain the actual media data; instead, it acts as an index or table of contents, pointing to the individual media segments stored on a web server. It can also contain information about encryption keys, subtitles, and other stream-related data. HLS is widely used for streaming video content over the internet, particularly on mobile devices and web browsers, due to its adaptability and compatibility.