This chapter discusses the issues of security and privacy in a cloud environment. Although cloud computing has the same security and privacy issues as a conventional computing facility, the chapter focuses on new types of security and privacy problems that arise in cloud. The chapter discusses traditional security methods, and explains why they do not suffice for cloud systems. In particular, it describes perimeter security used in a traditional environment, and a zero-trust approach needed for a cloud environment. The chapter covers Identity Management (IdM) and Privileged Identity Management (PAM) technologies that support the zero-trust approach. In addition, the chapter considers artificial intelligence (AI) and its effect both on security attacks and security defenses. The chapter goes on to discuss privacy in a cloud environment, and considers back doors and side channels. It explains that even revealing statistical aggregate data may inadvertently violate privacy by allowing outsiders to deduce information about individuals. The chapter points out that a tenant in a data center needs to work together with the cloud provider on security and privacy.