DVD region code
DVD (digital versatile disc) region codes are a digital rights management technique designed to allow rights holders to control the international distribution of a DVD release, including its content, release date, and price, all according to the appropriate region.
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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, multiple codes (multi-region), or all codes (region free).