A certification standard controlled and operated by THX Technologies. It covers certification of both cinemas and home entertainment equipment to meet given minimum standards. Originally, on the home entertainment front, there was just one standard: 'THX Certified'. But in recent years this has been replaced by several levels of standards... see the THX website for a full explanation. Note that many brands and products which could easily achieve THX certification decline to seek it for reasons of brand self-respect, or to avoid the cost involved, so THX certification does not necessarily mean that a piece of equipment is superior.