The healthy human eye has a resolving power of about 200 micrometers. Most cells and all organelles, the various structures within the cell, are much smaller than that. Microscopes, which come in many different designs, are intended to improve the resolution of the human eye and thus open up a world not visible through casual observation. Not only do they allow for visualization of small structures, but they also can be used as physiological and analytical tools. The photomicrographs here demonstrate different types of information about biological samples that can be obtained with different kinds of microscopes in combination with specialized techniques.