There are two sections. The first section teaches you how to initially set your grind range and coffee doses. In the US, the prevalence of latte drinking has resulted in many cafes using grind settings that are much too coarse, and doses that are much too high, for straight espresso. The result is that they taste much too bitter and sour. The second section teaches you how to analyze the taste of the shot in a way that allows you to adjust the taste balance to your liking. This is the way the best baristas fine tune their shots. Knowing which taste details go with which shot preparation details is the fastest way to improve your skills.