This has led to a variety of attempts to restrict children's access to Internet pornography such as the 1996 Communications Decency Act in the United States. Some companies use an Adult Verification System (AVS) to deny access to pornography by minors. However, most Adult Verification Systems charge fees that are substantially higher than the actual costs of any verification they do (for example, in excess of $10/month) and are really part of a revenue collection scheme where sites encourage users to sign up for an AVS system, and get a percentage of the proceeds in return.