DVD region codes are a digital rights management technique designed to allow film distributors to control aspects of a release, including content, release date, and price, according to the region.
This is achieved by way of region-locked DVD players, which will play back only DVDs encoded to their region (plus those without any region code). The American DVD Copy Control Association also requires that DVD player manufacturers incorporate the regional-playback control (RPC) system. However, region-free DVD players, which ignore region coding, are also commercially available, and many DVD players can be modified to be region-free, allowing playback of all discs.
DVDs may use one code, a combination of codes (multi-region), every code (all region) or no codes (region free).