The computer and operating system safeguards described in this book protect information very effectively as long as the information remains safely in the computer, under the operating system's control. But, in the world of networks, and the Internet, information is increasingly on the movebeing shared and communicated among different users on different systems across the globe. Information that's protected securely by an operating system becomes much more vulnerable when it's being transmittedover telephone lines or network connections, via satellite or microwave. Whether you are sending your thoughts via electronic mail, presenting your new sales plan using a shared document session, or simply transferring data files, once the information enters the wild, your materials are potentially available to anyone. Instead of being available to only a relatively small population of users within your own organization, your computer system potentially becomes open to attack by anyone who has access to a modem or a network connection. Appropriate steps, such as are detailed in this chapter, must be taken.