This lecture covers weak bars, the Lindblad resonances, orbit families in realistic bars, the collisionless Boltzmann equation, the distribution function of stellar systems, solutions of the collisionless Boltzmann equation, stellar orbits in weak rotating bars, resonances, and problematic terms. It also discusses the Miyamoto-Nagai and Plummer potential models, Lindblad resonances, and equilibria of collisionless systems. The instructor emphasizes the importance of self-consistent galaxy models and the assumptions made in studying large stellar systems.