OGG Vorbis is a free, open, patent-unencumbered audio format. That's why it turns up wherever licensing matters: Unity and Godot projects, Linux distributions, Wikipedia's audio files, and plenty of web apps. Quality-wise it sits between MP3 and AAC, and at moderate bitrates it comfortably beats MP3.
Files are encoded at Vorbis quality level 5, which lands around 160 kbps variable bitrate — the usual choice for music that has to sound good without being large.
Where OGG is the right answer
Game engines are the biggest reason people convert to OGG — Unity, Godot and many audio middleware tools treat it as a first-class format with no licensing footnotes. It's also the usual pick for open-source software and for sites that want good compression without touching patented codecs. For everyday listening on consumer devices, MP3 or M4A will get you further.