The SEM is a large machine that is kept in a very clean room and requires a skilled technician to operate it. SEMs use electrons to produce very highly magnified images of tiny objects. An electron is a part of an atom -- the building block of matter (anything that can be touched physically). The electron is a tiny bit of electrically charged stuff found in the atom. An electron is so tiny that a small object probably has more than a quadrillion (1,000 billion or a million millions) of them in it!
To examine a sample using an SEM, it first has to be coated with a thin layer of gold. Gold is used because the sample needs to be able to conduct electricity (electrons). SEMs shoot electrons (from an "electron gun") through a series of magnetic lenses that focus the electrons on the sample. Sensors then build an image of the object using by detecting the electrons that are knocked loose when the electron beam hits the sample.
Archaeologists can use SEMs to look at the pattern of wear on ancient teeth to determine diet, look at the number of folds in metal work to determine how it was made, or look at pollen to identify the types of plants that lived nearby. SEM pictures are often very beautiful.
