The title is pretty self explanatory. I'm looking for a book about different forms of government just to satiate my own curiosity. I have a very basic understanding about most forms of government and wish to learn more about the systems of government that different nations around the world operate and also just simply how those systems operate.
There's an excellent two-volume work on just this topic by Francis Fukuyama. The first is The Origins of Political Order: From Prehuman Times to the French Revolution and the second is Political Order and Political Decay: From the Industrial Revolution to the Globalization of Democracy.