This article reviews the achievements of both atomic resolution and subnanometer (molecular) resolution
in ambient conditions by atomic force microscopy (AFM). The principles of AFM and AFM operation
modes are first introduced. The concept of resolution is then discussed. Various types of tipsurface
forces, particularly the forces prominent in liquid and in air, are introduced. Different viewpoints on
the conditions for achieving atomic/subnanometer resolution are reviewed. The important issues of
reproducibility and artifacts are discussed in depth, with many examples from the literature. The central
portion of this article is a critical review of the published results of atomic resolution, dating from 1993 up
to 2007. The achievements of subnanometer resolution on biological samples are then briefly overviewed.
Examples are given to demonstrate how to obtain reliable structural information from lattice resolution
or pseudo-atomic resolution topographs. Finally, the challenges of AFM as a trustworthy high resolution
technique are discussed.