Blu-ray protections including Blu-ray copy protections and region code are technologies used on Blu-ray releases to protect them from unauthorized viewing or copy.

Following are almost all Blu-ray protections we know in the current:
*AACS (Advanced Access Content System): A standard for content distribution and digital rights management, used as the access restriction scheme for HD DVD and Blu-ray disc to restrict access and copy.
*BD+: A component of the Blu-ray Disc Digital Rights Management system, intending to prevent unauthorized copy of Blu-ray discs and the playback of Blu-ray media by unauthorized devices.
*RC (Region Code): A digital rights management technique designed to allow film studios to control aspects of a release, including content, release date, and price, according to the region.  Almost all Blu-ray discs are encoded with a region code restricting the area of the world in which they can be played.
*BD-Live: A new technology for Blu-ray that uses internet to extend movie viewing experience with online chat, trivia game, exclusive downloadable content, and other online bonus. It requires that the Blu-ray player must support BD-Live. And the playback of the copy of disc with this protection always fails.
*UOP (the User Operation Prohibition): A form of use restriction used on Blu-ray/DVD discs for copyright notices or warnings, such as FBI warnings in the United States and "protected" commercials which can't be skipped.  

Such Blu-ray protections are annoying when they affect your viewing experience, or when you just simply want to make a backup. Lucky that Passkey for Blu-ray can remove all of them, including newly released AACS MKB v23, 3D BD+, etc. as Passkey is being updated all the time.