A microscope is an instrument

Laboratory equipment

Laboratory equipment refers to the various tools and equipment used by scientists working in a laboratory. These include tools such as Bunsen burners, and microscopes as well as speciality equipment such as operant conditioning chambers, spectrophotometers and calorimeters...

 used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy

Microscopy

Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...

. Microscopic

Microscopic

The microscopic scale is the scale of size or length used to describe objects smaller than those that can easily be seen by the naked eye and which require a lens or microscope to see them clearly.-History:...

 means invisible to the eye unless aided by a microscope.

There are many types of microscopes, the most common and first to be invented is the optical microscope

Optical microscope

The optical microscope, often referred to as the "light microscope", is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest design of microscope and were possibly designed in their present compound form in the...

 which uses light

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

 to image the sample. Other major types of microscopes are the electron

Electron

The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

 microscope (both the transmission electron microscope and the scanning electron microscope

Scanning electron microscope

A scanning electron microscope is a type of electron microscope that images a sample by scanning it with a high-energy beam of electrons in a raster scan pattern...

) and the various types of scanning probe microscope.
The first microscope to be developed was the optical microscope, although the original inventor is not easy to identify.