Audio

What is a .ogg file?

A .ogg file is an Ogg Vorbis Codec Compressed Multimedia File. This is an audio format. Confusingly, this extension has been used by 7 different formats over the years — they're all listed below.

This extension has been used by more than one format

7 different formats have claimed .ogg over the years, so two files with the same extension aren't necessarily the same kind of thing.

How to open a .ogg file

VLC plays almost every audio format ever made.
Audacity opens it for editing.

The registry records this extension against Ogg Vorbis Codec Compressed Multimedia File, Ogg Multimedia Container, Ogg Theora Video and others, so software from that family is the most likely match.

How to convert a .ogg file

Export as .mp3 from Audacity or VLC for maximum compatibility.

MIME type

When a .ogg file travels over the web, servers label it with one of these MIME types:

audio/oggapplication/oggvideo/oggaudio/opusaudio/speex

What's a MIME type?

The technical record

For archivists, developers and the merely curious: these are the PRONOM registry entries for .ogg.