The Introduction argues that to understand European politics there are two premises that need to be accepted. Firstly, the interplay between European and national-level politics must be taken seriously. The two cannot be studied independently. Secondly, a theoretical model of politics is necessary to help us to make assumptions about politics explicit and to ensure that the arguments used are logically consistent. Models help us to zoom in on a particular aspect of politics and apply our analysis to real-life examples. It also helps us to spot the similarities and differences across political systems and governments so we can make comparisons. The Introduction answers the question: why focus on Europe? One of the most obvious reasons is that Europe is the home to the largest number and variety of democratic governments anywhere in the world.