Any of several microscopic techniques that are based on measuring the interaction between a very sharp-tipped probe and the surface of the sample. The probe repeatedly scans the sample surface in a systematic way (or the sample is moved beneath a static probe) and records the surface topography; deflections of the tip can be caused by various types of forces, including mechanical contact, electrostatic forces (as in atomic force microscopy), van der Waals forces, capillary forces, and magnetic forces (in magnetic force microscopy). The resulting data are processed by a computer to produce images, with resolutions of the order of a fraction of a nanometre. Widely used in chemistry, such techniques are now commonly used in biology to study biomolecules and cell surfaces at the nanometre scale. The most common variations are atomic force microscopy and scanning tunnelling microscopy.

http://www.chem.qmul.ac.uk/surfaces/scc/scat7_6.htm Elegant overview compiled by the Chemistry Department of Queen Mary University of London