A microscope is an instrument used to observe objects that are too small to be seen by the naked eye. Microscopy is the study of small objects and structures using this instrument. A microscope is something invisible to the naked eye, except with the aid of a microscope.

There are many types of microscopes, and they may be grouped in different ways. One method is to describe how the instrument interacts with the sample to create an image by sending a beam or electron to the sample on its optical path, or by scanning the sample surface and using the probe at a short distance from the sample surface. The optical microscope (also the first invention) is the optical microscope, which uses light to pass through a sample to produce an image. The other main types of microscope are fluorescence microscope, electron microscope (transmission electron microscope and scanning electron microscope) and various types of scanning probe microscope.