This chapter introduces the main topics in current Mediterranean climate research and contains a general description of the Mediterranean Climate. Its aim is to provide essential information and a comprehensive view. It also anticipates the data, research results and key findings that are presented in much more detail in the book chapters, to which the reader is directed for extensive discussion. In this chapter the regional climate system is introduced considering different time scales, from paleo-climate to centennial climate projection, attempting a seamless approach to the description of the evolution from past to future climate, and including not just the atmospheric variables but also the oceanic and land components. This chapter includes a discussion of the main open issues in the Mediterranean climate research and also briefly presents social-economic problems and vulnerabilities that are specific to the Mediterranean region.