Today's offered services in the World Wide Web increasingly rely on the disclosure of private user information. Service providers' appetite for personal user data, however, is accompanied by growing privacy implications for Internet users. Targeting the rising privacy concerns of users, privacy-enhancing technologies (PETs) emerged. One goal of these technologies is the provision of tools that facilitate more informed decisions about personal data disclosures. Unfortunately, available PET solutions are used by only a small fraction of Internet users. A major reason for the low acceptance of PETs is their lack of usability. Most PET approaches rely on the cooperation of service providers that do not voluntarily adopt privacy components in their service infrastructures.Addressing the weaknesses of existing PETs, this book introduces a user-centric privacy architecture that facilitates a provider-independent exchange of privacy-related information about service providers. This capability is achieved by a privacy community, an open information source within the proposed privacy architecture. A Wikipedia-like Web front-end enables collaborative maintenance of service provider information including multiple ratings, experiences and data handling practices.In addition to the collaborative privacy community, the introduced privacy architecture contains three usable PET components on the user side that support users before, during and after the disclosure of personal data. All introduced components are prototypically implemented and underwent several user tests that guaranteed usability and user acceptance of the final versions. The elaborated solutions realize usable interfaces as well as service provider independence. Overcoming the main shortcomings of existing PET solutions, this work makes a significant contribution towards the broad usage and acceptance of tools that protect personal user data.