For many years, the concept of an authoritarian regime was considered to be one large category, with little understanding of how these regimes differed. The study of authoritarian regimes has come a long way since. Though all authoritarian regimes share in common that there is no turnover in power of the executive, there are considerable differences that distinguish autocracies. Authoritarian regimes today are increasingly attempting to use ‘democratic’ institutions to prolong their rule. This has led to a rise in competitive authoritarian regimes, or hybrid regimes. In spite of these changes, authoritarian regimes are more robust than ever. This chapter explains the different ways in which authoritarian regimes are categorized. The chapter then explains how the different types of authoritarian regimes perform, and what factors make them more durable. As the chapter demonstrates, autocratic regimes have become increasingly better equipped to maintain themselves.