The proliferation of mobile devices has given rise to novel user-centric applications and services. In current mobile systems, users gain access to remote servers over mobile network operators. These operators are typically assumed to be trusted and to manage the information they collect in a privacy-preserving way. Such information, however, is extremely sensitive and coveted by many companies, which may use it to improve their business. In this context, safeguarding the users’ privacy against the prying eyes of the network operators is an emerging requirement. In this chapter, we first present a survey of existing state-of-the-art protection mechanisms and their challenges when deployed in the context of wired and wireless networks. Moreover, we illustrate recent and ongoing research that attempts to address different aspects of privacy in mobile applications. Furthermore, we present a new proposal to ensure private communication in the context of hybrid mobile networks, which in...