This lecture covers the radiation-reaction force, the Lorentz covariant formulation of electrodynamics, Maxwell equations, and the Lagrangian formulation of electrodynamics. It delves into the concept of radiation-reaction force and the conservation of momentum, exploring the challenges in understanding the radiated momentum. The lecture also discusses the correct expressions for the force, the Schott term, and the non-relativistic limit, highlighting the importance of integrating constants in the analysis.