The invention of scanning tunneling microscopy (STM) in 1982 revolutionized surface analysis by providing atomic-scale surface imaging of conducting and semiconducting materials. Shortly after that, atomic force microscopy (AFM) was introduced as an accessory of STM for high-resolution imaging of surfaces independent of their conductivity. Mechanical force interactions between a sharp tip placed at one end of a micro fabricated cantilever and a sample surface were employed for imaging in this method. In the past decade, AFM has developed into a leading scanning probe technique applied in many fields of fundamental and industrial research. The progress of AFM has been made possible by implementation of an optical level detection scheme, which allows precise measuring of the cantilever deflection caused by the tip-sample forces, by mass microfabrication of probes consisting of cantilevers, and by developments of oscillatory imaging modes, particularly, Tapping ModeTM.