Microscopy is the technical field of using microscopes to view samples or objects. There are three well-known branches of microscopy, optical, electron and scanning probe microscopy.

Optical and electron microscopy involve the diffraction, reflection, or refraction of electromagnetic radiation/electron beam interacting with the subject of study, and the subsequent collection of this scattered radiation in order to build up an image. This process may be carried out by wide-field irradiation of the sample (for example standard light microscopy and transmission electron microscopy) or by scanning of a fine beam over the sample (for example confocal laser scanning microscopy and scanning electron microscopy). Scanning probe microscopy involves the interaction of a scanning probe with the surface or object of interest. The development of microscopy revolutionized biology and remains an essential tool in that science, along with many others including materials science and numerous engineering disciplines.

For more information about Microscopy, read the full article at Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.