This lecture covers the interaction between the tip and sample in Atomic Force Microscopy (AFM), focusing on the Van-der-Waals force, hysteresis, contact AFM, non-contact AFM, and feedback mechanisms. It also discusses the operation of contact AFM, laser beam movement detection, AFM feedback, and the impact of tip size on image resolution. Additionally, it explores the force regimes in non-contact AFM, resonances of the cantilever, and the importance of plane-fit corrections in image treatment.