Cyber-physical systems (CPSs) are systems that integrate sensing, computation, control, and networking into physical systems. They have transformed the way we interact with engineered systems and herald many emerging technologies and applications, including smart grids, connected and autonomous vehicles, cyber manufacturing, and intelligent healthcare systems. One essential challenge of designing CPSs is the interdependencies between the cyber and the physical layers of the system. In particular, the strong coupling between the two layers provides adversaries new opportunities to compromise the physical assets through the cyber system. Traditional methods, such as cryptography and intrusion detection systems, are not sufficient to safeguard the CPSs. Instead, it is vital to develop a cross-layer approach that enables interdependent impact-aware security defense strategies and cyber-aware resilient control strategies. To this end, this book presents two methodologies for the design. The first one focuses on cryptography and control theory, which are used to address control and estimation problems where the outsourcing of computations is possible. The second one focuses on the interconnection between game theory and control theory to resolve design problems with explicit attack models. This chapter gives an overview of the book and discusses literature related to the proposed cross-layer approach.