A microscope is an instrument used to investigate objects that are too small to see with the naked eye. The optical microscope was the first to be invented and remains the most common to date. It magnifies images of small samples by using visible light and a system of lenses. Most microscopes contain the same components: an ocular lens, objective, focus wheel, frame, light source, diaphragm, and stage.

It was on this day, September 7, 1590, that the first ever microscope was said to be invented in Middelburg, Netherlands by Dutch spectacle-makers Hans Janssen and his son, Zacharias Janssen. However, it was not until the 1660s and 1670s that it was used for research in Italy, England, and Holland. From its creation until present day, there have been many types of microscopes invented. There are optical, electron, and scanning probe microscopes to name a few. They are used in microbiology, nanophysics, biotechnology, pharmaceutical research, and their use has been imperative in medical diagnosis.