Everything you always wanted to know about extinction but were afraid to ask

Twenty two years ago Cardelli et al. published their seminal paper on Galactic extinction laws. In the first part of my talk I will explore that (often quoted but also often misunderstood) paper and detail its strengths and weaknesses. In the second part I will describe the two datasets that have finally allowed the Cardelli et al. laws to be tested to their limit and I will present a new family of extinction laws derived from the new data that do a better job in describing extinction in the optical range.