Privacy has no definite boundaries and it has different meanings for different people. It is the ability of an individual or group to keep their lives and personal affairs out of public view, or to control the flow of information about themselves. Privacy is sometimes related to anonymity although it is often most highly valued by people who are publicly known. Privacy can be seen as an aspect of security—one in which trade-offs between the interests of one group and another can become particularly clear.
Taken from http://en.wikipedia.org/wiki/Privacy.