HDCP (High-bandwidth Digital Content Protection) is a type of digital copy protection technology designed to prevent unauthorized duplication of high-definition (HD) video and audio content as it travels across digital interfaces such as HDMI, DVI, or DisplayPort. The technology works by encrypting the video and audio data as it is transmitted from a source device (such as a Blu-ray player) to a display device (such as a television) and requiring both devices to have HDCP authentication keys. If either the source or the display device is not HDCP-compliant, the content will not be displayed, in order to prevent piracy. HDCP has been widely adopted in the consumer electronics industry and is used by many major studios and content providers to protect their copyrighted material.
https://en.wikipedia.org/wiki/High-bandwidth_Digital_Content_Protection