There are several standards and formats for DVDs, videos, and video games worldwide.
DVDs
Currently, there are six global regions that identify where specific DVDs are compatible with the players typically sold in that region. The majority of all current titles play only in one specific region unless otherwise noted.
On amazon.fr you can purchase DVDs encoded for Region 2 (French releases and U.K. imports) and DVDs encoded for Region 1 (U.S. imports).
