MKVToolnix is a utility package created for multimedia edition; more specifically, the edition of extension of MKV file (or Matroska).

Matroska is a container format of other ‘sub formats’, so it admits both codified audio and video under the numerous known codecs.

Such utilities offer the possibility of visualizing codecs incorporated in the MKV file, creating new containers with audio and video flows in different formats, extracting audio tracks or even dividing the MKV in several smaller files.

As you may notice, these are the same functions offered by similar programs that work with videos and codifiers, but MKVToolnix focuses on the multimedia format Matroska.