Also called: M3U URL, M3U8.
M3U started as a simple playlist format for audio files. The extended version, which begins with the line #EXTM3U and describes each item with an #EXTINF line, became the most widely supported way to load IPTV channels into a player app.
An IPTV provider usually gives you an M3U link rather than a file. Pasting that link into an app loads the whole channel list; a separate EPG URL can then be added for the TV guide. M3U8 is the same format saved with UTF-8 text encoding.
M3U works almost everywhere, including VLC, but it is a single list: on-demand movies and series are often less organised than with an Xtream Codes login, which apps can split into live TV, movies and series automatically.
How does M3U playlist apply to SynexaTV?
Every SynexaTV subscription can be used as an M3U playlist or with Xtream Codes — support sends whichever your app needs.
For background and history, see M3U playlist on Wikipedia.