ABSTRACT
This chapter introduces the scaling laws and their empirical research in urban studies. It summarises around 50 indexed research outputs by showing the coefficient exponents of 41 urban variables. Potential reasons behind power laws linking urban population size with such variables are briefly exposed. Beside planning and policies enhancing and limiting, respectively, positive and negative effects predicted by urban scaling evidences, scaling laws can also be used to build a fairer evaluation of the performance of cities, measuring how well a city is doing in respect to a typical city of her size in her region at her time. Critical points limiting urban scaling research are listed in the concluding section.
