DVD video discs may be encoded with a region code restricting the area of the world in which they can be played. Discs without region coding are called all region or region 0 discs.

The commercial DVD player specification requires that a player to be sold in a given place not play discs encoded for a different region (region 0 discs are not restricted). The purpose of this is to allow motion picture studios to control many aspects of a release, including content, release date, and, especially, price, according to the region. Many DVD players are or can be modified to be region-free, allowing playback of all discs.

The term "Region 0" also describes the DVD players designed or modified to incorporate Regions 1–6, thereby providing compatibility with most discs, regardless of region. This apparent solution was popular in the early days of the DVD format, but studios quickly responded by adjusting discs to refuse to play in such machines. This system is known as "Regional Coding Enhancement".

Implementations of region codes

Standalone DVD players

Usually a configuration flag is set in each player's firmware at the factory. This flag holds the region number that the machine is allowed to play. Region-free players are DVD players shipped without the ability to enforce regional lockout (usually by means of a chip that ignores any region coding), or without this flag set, usually known as ALL REGION FREE COMPACT MP3 AC-3 DVD PLAYER NTSC/PAL. This was partly a result of a landmark ACCC case in which the High Court of Australia ruled that region lockouts breached fair trade and market competition practices.

However, if the player is not region-free, it can often be unlocked with an unlock code entered via the remote control. This code simply allows the user to change the factory-set configuration flag to another region, or to the special region "0". Once unlocked this way, the DVD player allows the owner to watch DVDs from any region. Many websites exist on the Internet offering these codes, often known informally as hacks. Many websites provide instructions for different models of standalone DVD players, to hack, and their factory codes.

Computer DVD drives

Older DVD drives use RPC-1 firmware, which means the drive allows DVDs from any region to play. Newer drives use RPC-2 firmware, which enforces the DVD region coding at the hardware level. These drives can often be reflashed or hacked with Australia and New Zealand (hardware region coding prohibited by law in these countries) RPC-1 firmware, effectively making the drive region-free. However, this usually voids the warranty.

If you insert a DVD in to some computer drives, you can change the region code to play each DVD. (i.e. change region code up to 5 times)

Software DVD players

Most freeware and open source DVD players, such as VLC, ignore region coding. Most commercial players are locked to a region code, but can be easily changed with software.

Other software, known as DVD region killers, transparently remove (or hide) the DVD region code from the software player. Some can also work around locked RPC-2 firmware.

DVD Discs

One can circumvent the region coding of a DVD disc by burning a copy that adds flags for all region codes, creating an all-region DVD. DVD backup software can do this, and can usually remove Macrovision, CSS, and disabled user operations (UOPs) as well.

Old Portuguese DVD Movies

Usually these are region free or all region or region 0 discs. As they are Black and White movies, they have not NTSC/PAL problem.