Privacy
• On a multi-user system, each user must be limited to just the data that she is permitted to access. • Without protection provided by the operating system, any user or application running on a system could access any of the data stored on the system, without the knowledge or approval of the data’s owner. – For example, hackers often use popular applications such as screen savers as a way to gain access to personal emails, telephone numbers, and credit card data stored on the system. • For privacy, an operating system must prevent untrusted code from accessing unauthorized data.