A complete list of current regions are as follows:

Table of region codes referenced from the February 3, 2001 DVD FAQ for the rec.video.dvd newsgroups.

Region free DVD players (such as the Apex AD-600A) are set to region 0 and will attempt to play any disc. RCE (Region Code Enhanced) discs seem to be able to detect region 0 players and refuse to play, displaying instead a static screen explaining the region scheme.

The Patriot starring Mel Gibson is one such disc. Note: The DVD FAQ says that Warner Bros. wasn't the first producer of 'smart-discs' and that a number of DVDs already included this feature (There's Something About Mary and Psycho, for example).

In order to circumvent this protection, one must reset the player region code to whatever the disc expects. If the player cannot be reset, the viewer is SOL.

A number of online interest groups argue that region codes act only as a trade barrier.

Addendum, prompted by a message from Servo5678: There's a misconception floating about that there's an additional region, designated solely for the International Space Station. This isn't the case (consider how much of a pain it would be to provide a movie library encoded for a previously non-existent region) -- instead, their DVD player (a Sony FX1) has been modified to play discs from regions 1 through 6.1