This lecture focuses on scalar linear second order ordinary differential equations (ODEs), exploring how to systematically solve them as initial value, boundary value, and eigenvalue problems. The instructor introduces various special functions, such as orthogonal polynomials and Bessel functions, which are essential in physics. The lecture also discusses the importance of studying second order differential operators in physics, providing examples like Newton's second law, Poisson's equation, wave equation, and Schrödinger's equation. The systematic procedure for solving scalar linear second order ODEs is explained, involving finding linearly independent solutions to the homogeneous equation and a particular solution to the inhomogeneous ODE.