This lecture covers the concept of heat convection, focusing on boundary layers and flow regimes. It explains how heat is transmitted by convection from a surface to adjacent molecules, distinguishing between natural and forced convection. The lecture delves into the characteristics of laminar and turbulent flow regimes, emphasizing the importance of forced convection in energy transport. It discusses the hydrodynamic boundary layer, where fluid movement is influenced by viscous forces, and the thermal boundary layer, crucial for heat transfer calculations. The determination of Nusselt, Biot, Prandt, and Reynolds numbers is explored to understand heat transfer mechanisms. The lecture concludes with practical examples and empirical relations for different flow scenarios.