A regional lockout (or region coding) is a class of digital rights management preventing the use of a certain product or service, such as multimedia or a hardware device, outside a certain region or territory. A regional lockout may be enforced through physical means, through technological means such as detecting the user's IP address or using an identifying code, or through unintentional means introduced by devices only supporting certain regional technologies (such as video formats, i.e., NTSC and PAL).
A regional lockout may be enforced for several reasons, such as to stagger the release of a certain product, to avoid losing sales to the product's foreign publisher, to maximize the product's impact in a certain region through localization, to hinder grey market imports by enforcing price discrimination, or to prevent users from accessing certain content in their territory because of legal reasons (either due to censorship laws, or because a distributor does not have the rights to certain intellectual property outside their specified region).
DVD region codeBlu-ray#Region codes and Universal Media Disc#Region coding
The DVD, Blu-ray Disc, and UMD media formats all support the use of region coding; DVDs use eight region codes (Region 7 is reserved for future use; Region 8 is used for "international venues", such as airplanes and cruise ships), and Blu-ray Discs use three region codes corresponding to different areas of the world. Most Blu-rays, however, are region-free. Ultra HD Blu-ray discs are also region-free.
On computers, the DVD region can usually be changed five times. Windows uses three region counters: its own one, the one of the DVD drive, and the one of the player software (occasionally, the player software has no region counter of its own, but uses that of Windows). After the fifth region change, the system is locked to that region. In modern DVD drives (type RPC-2), the region lock is saved to its hardware, so that even reinstalling Windows or using the drive with a different computer will not unlock the drive again.