Why do we value privacy, and why should we value it? Against the backdrop of modern, liberal societies, a normative theory of the private is established, which views the protection of the private as functionally related to the possibility of an autonomous life. Different dimensions of privacy are developed: decisional privacy concerning individual choices and lifestyles; informational privacy as control over knowledge that others have about a person; and local privacy regarding protected spaces. Issues of privacy in relationships are discussed, as well as questions of data protection and the normative difficulties in the relationship between public and private.