A list, not a video format
An M3U file is a text document that points a player toward media. It does not contain the television programme itself. In an IPTV directory, an entry usually has an EXTINF line describing the channel and a following line containing the media address.
That distinction matters: opening an M3U does not guarantee playback. Every referenced source still has its own protocol, availability, access rules and browser compatibility.
The metadata viewers depend on
Attributes such as tvg-id, tvg-logo and group-title connect a raw address to a programme guide, artwork and category. They are conventions rather than proof of identity. A responsible directory validates them and keeps editorial corrections separate from the imported source.
Use playlists with care
A playlist may include signed URLs, usernames or temporary tokens. Treat it like a private configuration file unless its publisher says otherwise. AdiosTV parses user playlists locally and never turns a pasted list into a public directory automatically.