Child pornography refers to pornographic material depicting children. The production of child pornography is widely regarded as a form of child sexual abuse and as such these images and videos are illegal in most countries. Some outlaw only production, while others also prohibit distributing, possessing, and accessing child pornography. Prohibition generally covers visual representations of sexual behaviour by children under a given age but may also include all images of nude children, unless an artistic or medical justification can be provided.