Taxes form the financial backbone of modern societies. They not only raise public revenues, but they are also an effective means of curbing the climate crisis and economic inequalities. Deciding who and what to tax and how to distribute the financial burden is therefore highly political. The aim of this chapter is to provide a conceptual overview of the main political and economic forces driving change in the tax state and the distributional implications that different forms of taxation entail. The chapter begins with an overview of the different forms of taxation, continues with a descriptive overview of some key patterns and discusses the main theoretical explanations that may account for the different developments of the tax state. It concludes with suggestions for future research.