This chapter introduces the basic laws for winds in the boundary layer. These laws are important for understanding wind flow modelling and wind resource assessment, particularly in recent years, because the increasingly larger sizes of wind turbines and wind farms have led to much more complicated interactions between the turbines and the lower atmosphere. Wind speed‐up is stronger in more stable conditions, except for very stable stratification, which may completely block the flow. The dimension and orientation of the mountains also determine the air‐terrain interactions, and so does the wind speed. The first offshore wind power project was installed off the coast of Denmark in 1991.The chapter presents the characteristics of offshore winds in the marine atmospheric boundary layer (MABL) and applications of offshore wind resource assessment and wind turbine layout design.