1. What are Behavior Trees? 2. How Behavior Trees Generalize and Relate to Earlier Ideas 3. Design principles 4. Extensions of Behavior Trees 5. Analysis of Efficiency, Safety, and Robustness 6. Formal Analysis of How Behavior Trees Generalize Earlier Ideas 7. Behavior Trees and Automated Planning 8. Behavior Trees and Machine Learning 9. Stochastic Behavior Trees 10. Concluding Remarks