Child pornography is the illegal use of minors in pornographic photos or films. Defense for these charges include a thorough understanding of whose computer or digital video the material exists on, where the material came from, and other possible reasons why the material is present, including other users, viruses, hacking, human error, and others. Punishment for being found guilty of possessing child pornography can include imprisonment for up to ten years and being required to register as a sex offender.