8.Protection and security. The owners of information stored in a multiuser or networked computer system may want to control use of that information. When. several separate processes execute concurrently, it hould not be possible for one process to interfere with the others or with the operating system itself. Protection iiwolves ensuring that all access to systerr1-resources 1S -controlled. Security of the system from outsiders is also important. Such security starts with requiring each user to authenticate himself or herself to the system, usually by means of a password, to gain access to system resources. It extends to defending external I/0 devices,including modems and network adapters, from invalid access attempts and to recording all such connections for detection of break-ins. If a system is to be protected and secure, precautions must be instituted throughout it. A chain is only as strong as its weakestlink.