Tree diagrams can be used to systematically list all possible outcomes of sequential events. They are illustrated with branches representing different options at each step. Examples provided include using a tree diagram to show the possible outcomes of coin tosses or the gender combinations of three children. Tree diagrams can also be used to count the number of possible outfits one could make from different shirt, tie, and pants options or meals that could be ordered from various main dish, salad, and dessert choices. The document provides guidance on creating and using tree diagrams to explore outcomes and possibilities.