This paper reviews the theoretical definitions on the concepts of the rule of law, democracy and economic freedom, as well as a large number of measurement projects and indexes that try to quantify them. These three dimensions of liberal democracy many times overlap and are not always well differentiated both at a theoretical and quantitative level, which is likely one of the causes of the conflicting results of the democracy-growth literature. The main goal of this paper is to serve as a first step towards opening the black box of democracy, and thus better capture the mechanisms through which the different attributes of the institutional architecture of a country affect its economic performance.