DMCA, or the Digital Millennium Copyright Act, is a U.S. copyright law that works to limit liability of online service providers for copyright infringement that happens by third parties on the service, while criminalizing producing or distributing online methods of circumventing copyright laws.
Online platforms such as YouTube can utilize DMCA takedown notices to help limit its liability if a user uploads infringing material, while end users can submit takedown notices if their copyright is infringed.
Learn more about DMCA in our DMCA article.