Final answer:
The DMCA is the act that defines legal prohibitions against the circumvention of copyright protection measures and safeguards copyright owners' exclusive rights.
Step-by-step explanation:
The act that defines legal prohibitions against circumvention of the technological protection measures employed by copyright owners to protect their works and against the removal or alteration of copyright management information is the DMCA (Digital Millennium Copyright Act). This federal law addresses various aspects of copyright law and is crucial for maintaining a legal monopoly for copyright holders over their creations, effectively supporting the concept of intellectual property protection. It contributes to preventing activities such as unauthorized copying and distribution of copyrighted material, ensuring that creators and copyright owners have exclusive economic rights to their work.