XD is a format that has been coined I believe by cinemark. It stands for extreme digital experience. Overall it means you will have bigger screens, better speakers (premium sound quality) and in most cases excellent seating! P.S.: Not all XD cinema movies are necessarily 3D. They can be regular 2D XD movies too.
XD just describes the overall theater experience. The size of the screen, speaker types and possibly the luxury recliners. They sometimes will do a 3D showing of a movie in the XD theater.
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