An M3U8 file is a UTF-8 encoded audio or video playlist file that is primarily used to instruct a media player how to locate and play specific media content. They are plain text files that contain references to the location of the media file, which can be an absolute path, a relative path, or a URL.

For example, an M3U8 file might reference an online file from an Internet radio station, or be used to create a playlist of personal music or videos. By opening the file, the media player is able to play the specified content in order, following the instructions in the list.

It is important to note that an M3U8 file itself does not contain the actual audio or video data, but rather provides information about the location and order of the media files. Therefore, when playing an M3U8 file, it is important to ensure that the referenced media file is available and the path is correct.

In addition, M3U8 files are widely used in HTTP Live Streaming (HLS) technology, which is used to implement adaptive bitrate streaming media playback. This technology allows the player to adjust the quality of the media based on the user's network conditions, providing a more fluid viewing experience.

Many media players and software support the M3U8 file format, including VLC, iTunes, etc. These players can parse the information in the M3U8 file, locate and play the corresponding media content.

Most text editors (such as Notepad in Windows) can open and view the contents of M3U8 files. However, Notepad can only display the reference paths in the file, and cannot directly play the audio or video files, because the text editor and professional media players or media management programs have different functionalities.

If you are looking for a suitable program to open and play M3U8 files, the following software may be worth considering: VLC Media Player, iTunes, or Songbird. For Linux users, XMMS can be used, and for Mac users, CocoModX can be selected. There are also some compatible programs available for Windows.

You can also quickly open M3U8 files using online tools. For example, using an M3U8 online player, you can directly play the M3U8 file link online. However, please note that the website may not be able to be used if your computer or other devices have local M3U8 files stored. Only when you have a valid file URL and the content it references is online, can this type of online tool be used.