Privacy has emerged as a key concern for companies that deal with Personal Information (PI) since they need to comply with certain privacy requirements. Unfortunately, these requirements are often incomplete or inaccurate due to the vagueness of the privacy concept. This paper tries to tackle this problem, contributing to the philosophical foundations of privacy by addressing several foundational questions such as What is privacy? What makes information a PI? Is PI a property? Do we own our PI? To what extent we are entitled to protect our PI? How do we protect our PI? After answering the aforementioned questions, we characterize the privacy concept that allows providing a more precise and meaningful conceptualization of privacy requirements, which may improve dealing with them during the design of privacy-aware systems.