Microscope is an instrument that magnifies extremely small objects so they can be seen easily. It ranks as one of the most important tools of science. Physicians and biologists, for example, use microscopes to examine bacteria and blood cells. Materials scientists and engineers use microscopes to study the crystal structures within metals and alloys (metal mixtures), and to examine computer chips and other tiny electronic devices. Biology students observe algae, protozoa, and other single-cell organisms under a microscope.