This chapter provides a comprehensive overview of the aerodynamics of horizontal-axis wind turbines (HAWTs), focusing on steady-state aerodynamics. It begins with an introduction to wind turbine power production and the importance of understanding aerodynamic forces. The chapter then delves into classical analytical approaches, including the actuator disc model, momentum theory, blade element theory, and blade element momentum (BEM) theory. The actuator disc model is introduced as a simple method to calculate power output and wind thrust, while momentum theory and blade element theory are detailed for their role in predicting rotor performance. BEM theory combines these methods to determine optimal blade shapes and performance parameters under steady operating conditions. The rotating annular stream tube analysis is discussed to account for rotational motion, and the relationship between wake velocities and wind velocities is established. Blade element theory is explained, considering the effects of rotor geometry and airfoil characteristics. The chapter also addresses tip losses, which are significant at the blade tips, and provides a method for correcting these losses in BEM theory. Finally, the chapter outlines a blade design procedure, emphasizing the importance of determining the geometric parameters for maximum power coefficient. The conclusion highlights the role of aerodynamic design in optimizing rotor performance and the advantages of BEM theory in performance analysis. The chapter concludes with acknowledgments and a list of references.This chapter provides a comprehensive overview of the aerodynamics of horizontal-axis wind turbines (HAWTs), focusing on steady-state aerodynamics. It begins with an introduction to wind turbine power production and the importance of understanding aerodynamic forces. The chapter then delves into classical analytical approaches, including the actuator disc model, momentum theory, blade element theory, and blade element momentum (BEM) theory. The actuator disc model is introduced as a simple method to calculate power output and wind thrust, while momentum theory and blade element theory are detailed for their role in predicting rotor performance. BEM theory combines these methods to determine optimal blade shapes and performance parameters under steady operating conditions. The rotating annular stream tube analysis is discussed to account for rotational motion, and the relationship between wake velocities and wind velocities is established. Blade element theory is explained, considering the effects of rotor geometry and airfoil characteristics. The chapter also addresses tip losses, which are significant at the blade tips, and provides a method for correcting these losses in BEM theory. Finally, the chapter outlines a blade design procedure, emphasizing the importance of determining the geometric parameters for maximum power coefficient. The conclusion highlights the role of aerodynamic design in optimizing rotor performance and the advantages of BEM theory in performance analysis. The chapter concludes with acknowledgments and a list of references.