There are eight basic types of runs that are practiced by runners of all levels everywhere. These evolved through a global trial-and-error process over many decades. They survived because they work. If you want to get the most out of the time you devote to training, you will need to learn and practice them, too. You can add all kinds of wrinkles to these formats — for example by combining two of them within a single session — but even in their most basic form, the workouts described on the following pages will help you become a better runner.