This is the software publisher's description.

VLC (initially VideoLAN Client) is a highly portable multimedia player for various audio and video formats, including MPEG-1, MPEG-2, MPEG-4, DivX, MP3, and OGG, as well as for DVDs, VCDs and various streaming protocols.

It also can be used as a server for unicast or multicast streams in IPv4 or IPv6 on a high-bandwidth network.

Version 0.8.6 adds, amongst other things, MacIntel support, improvements in the Audio CD playback (CDDB), and a a new AJAX HTTP interface. There are also Mac and Linux versions available.

This is the portable version which enables you to take your music and videos along with you, as well as something to play them on.