A transition is an interval between two regimes. Many political systems enter into a transition because their old regime, that is, their rules, procedures, and institutions, has become untenable, and they remain in the transition because no new regime succeeds in becoming consolidated. In the early twenty-first century political scientists became especially interested in the different patterns, forms, and outcomes of transitions from totalitarian and authoritarian regimes to democratic regimes. However, the various transitions do not always result in democratic regimes. Quite often a transition proceeds from one type of authoritarian regime to a different type of authoritarianism. When a transition is heading toward the inauguration of a democratic regime, the overall process is defined as democratization. It should be made clear, though, that not all democratizations give birth to democratic consolidation, that is, to regimes that can be considered both democratic and stable...