The author is a professional type designer and created some well known fonts - including Proxima Nova and Anonymous Pro. For someone that has spent much of his

The author is a professional type designer and created some well known fonts - including Proxima Nova and Anonymous Pro. For someone that has spent much of his life looking at and thinking about typefaces, I imagine it's trivial for him to accurately identify hundreds of varieties. I recommend "The Elements of Typographic Style" by Robert Bringhurst if you'd like to improve your type identification abilities. The appendices have a good, but by no means exhaustive, reference of some of the better known typefaces.