A DMCA takedown refers to a notice sent because a copyright owner believes someone has posted an infringement and they want it removed without the hassle of filing an infringement lawsuit. (It is sanctioned under the Digital Millenium Copyright Act.) The copyright owner typically notifies the web provider that hosts the site (the Internet Service Provider or ISP). The ISP (assuming they're not in Rumania, China, or some other country where the locals don't fear U.S. copyright lawyers) typically removes whatever is complained about -- for example, an infringing picture at a blog, an infringing movie at YouTube, etc. By "expeditiously" removing the infringing content, the ISP is given a "safe harbor" meaning that the ISP can't be sued for infringement.
After taking down the material, the ISP then may write to the individual user who maintains the blog, website, or YouTube account and inform them about the Notice to explain why the music, movie or eBook is now missing. The individual user then has the right to file a counter-notice.
What's an ISP? An Internet Service Provider (ISP) also sometimes referred to as an Online Service Provider (OSP) is any business that provides access to the Internet. That includes big access providers like AOL, Yahoo! and Google, or it can refer to companies that provide website hosting, commercial wi-fi services, or file-transferring (FTP) services.
The DMCA is often used by angry copyright claimants seeking to have an ISP remove infringing works under its "notice and takedown" procedures, described above. To protect against the unjustified use of this provision, Congress provided section 512(f), which permits Internet publishers to bring affirmative claims against copyright owners who knowingly and materially misrepesent that infringement has occurred. In a 2004 case, two ISPs successfully used this provision to fight back against a DMCA notice and takedown procedure instigated by Diebold over the republication of an email archive. The emails from Diebold engineers allegedly sounded an alarm over flaws in Diebold's electronic voting machines. A court ruled that the republication of the emails was a fair use because there was no commercial harm and no diminishment of the value of the works. (Online Privacy Group v. Diebold, 72 USPQ 2d 1200 (N.D. Cal. 2004).)
In 2008, a district court ruled that prior to requesting a takedown notice, a copyright owner must consider the likelihood of a claim of fair use. In that case, Universal Music issued a takedown notice for a video of a child dancing to the song, ‘Let's Go Crazy,' by Prince. The owner of the video claimed that because Universal didn't consider the issue of fair use, Universal could have not had a "good faith belief" they were entitled to a takedown. Faced with this novel issue, a district court agreed that the failure to consider fair use when sending a DMCA notice could give rise to a claim of failing to act in good faith. (Lenz v. Universal Music Corp. 572 F.Supp.2d 1150 (N.D. Cal. 2008)).
If you want to fight the notice -- many are abusive -- and you're willing to risk a court battle, consider a counter notice. If the complaining copyright owner fails to respond to your counter notice by filing a lawsuit, the ISP/OSP may re-post your content. These rules and procedures are part of the Digital Millennium Copyright Act.