Here is how the system works: A copyright holder uploads its works into a reference database, which then generates identification files by which uploaded videos are matched. When a user uploads a video onto YouTube, that video is matched with the identification file. If there is a “match” (more on that later), then the video is subject to whatever action the rights holder has decided to apply to it; for example, it could be blocked, “tracked” or “monetized.” If the video is blocked, the user will be notified, and can immediately contest the claim by clicking onto a link. Once YouTube receives the user contest, it will put the video back on the site. At that point, notice and takedown provisions of the Digital Millennium Copyright Act (DMCA) would kick in. If the copyright holder continues to want the video removed, it would have to send a takedown notice required by the DMCA. The user can send a counter-notice, whereupon the video would be reinstated, etc.