VLC media player is made by VideoLAN, a non-profit that grew out of a student project at the École Centrale Paris. It is free and open source, carries no ads, and opens most video and audio files without asking you to install a single codec.
What VLC is for
An MKV movie, a clip filmed on a phone, a DVD or a network stream: VLC plays them all in the same window. It can also convert a file to another format, record a stream, load external subtitles and shift them when they arrive too early or too late.
Who is it for?
Everyone. It is often the first program people install on a new PC, and the mobile app does the same job on Android and iPhone, including for videos stored on a NAS or a shared drive.
Download VLC safely
Use the official site, videolan.org, or the app stores. Modified copies circulate on download sites with unwanted software bundled into the installer; the original contains none.