The Internet is a communication network formed by computers in different places that deliver electronic information by passing it between them in a complex and flexible manner. The data can be exchanged in various ways, for example, by using an ordinary telephone network with a special device called a modem at the receiving and the transmitting points. The World Wide Web is a system in which people offer and receive information by using the Internet as the means by which they communicate. The Internet is a popular medium for pornography because it is private and anonymous at both the receiving and sending points. An unlimited supply of pornography from around the world can be accessed quickly and easily. Compared with paper publishing, it is cheap to produce, can be changed quickly, and can consist of any combination of still pictures, movies, sound, and text. In the United Kingdom, the determination of what is obscene is influenced by who might have access to it and whether they would be likely to be depraved and corrupted by it; therefore, material that might not be considered corrupting to an adult may be considered corrupting to a child. In Great Britain it is a criminal offense to provide and distribute such material. It is also an offense to store obscene images on a computer. In the United States, the Telecommunications Reform Bill makes it a crime to transmit indecent material that could be made available to anyone under 18 years old. Censorship is difficult on the World Wide Web, because such a mass of information, in different formats, is being transmitted worldwide. Pictures in electronic form are difficult to distinguish from any other data, and it can also be encrypted. Systems are now available that allow participation in a computer-generated world (virtual reality). This would create the illusion of active participation in pornographic activities. Private, unrestricted access to virtual reality on the Internet, therefore, produces a dimension of experience that may have an unprecedented power to fuel antisocial or criminal behavior in the real world.