A microscope is a scientific tool or instrument used for seeing objects that are many times too small to be seen with the naked eye. The oldest type of microscope is the optical microscope. This is still the most commonly found type and works by placing the object to be viewed plane and focusing one or more lenses over it.

A simple optical microscope contains a single lens above the item. Modern microscopes are more complex and powerful of which the most common is the compound microscope. This will contain at least two lenses, one above the object to be viewed and another before the eye. Optical microscopes with more than one lens can be quite powerful and magnify the object under observation by a factor of some hundreds. However if you want to get down to the subatomic level, there are stereo and electron microscopes than magnify by factors of well over ten thousand.