What does the DMCA tag mean?

What does the DMCA tag mean?
This tag describes copyright disputes involving the Digital Millineum Copyright Act (“DMCA”). Some common situations that involve the DMCA are disputes that relate to website notice-and-takedown procedures, the safe harbors provided for internet service providers under the DMCA, and claims involving circumvention of technical measures designed to control access to or copying of copyrighted works (like DRM).