Infringement is the unlawful use of a copyrighted work without permission. The copyright holder must prove that (1) his or her work is original (show proof of copyright registration, for example) and (2) that the defendant copied the work without permission. Most copyright cases are civil lawsuits, but criminal charges occasionally are brought, such as in cases of DVD piracy. The Copyright Office does not enforce copyright law, but its records can be used as evidence to support an infringement claim. In order to prevail on an infringement claim, the copyright owner does not have to prove that the work in question was copied precisely. Except in “piracy” cases, such direct copying seldom occurs. Infringement most often is shown by proving that the alleged infringer had access to the copyrighted work and that the alleged copy is substantially similar to the copyrighted work.
 4 Melville Nimmer & David Nimmer, Nimmer on Copyright § 13.01[A], at 13-6 (1999).
 Id. at § 13.01[B], 13-12.