What is a microscope and how is it used?

A microscope is a scientific instrument with one or more lenses that enhances the view of smaller objects, for example, microorganisms (bacteria) and microsopic materials, which are too small to be seen with the naked eye.

The eyepiece lens and objective lenses able to zoom in and out to enlarge and observe the specimens more clearly, with the objective lenses having a much better zoom-in ability. The eyepiece lens is at the top where you look into to observe the specimen. There are usually 3 or 4 objective lenses on a microscope held by a revolving nosepiece/turret, consisting of different times of zoom-in, e.g. 40x, 100x, 400x....

Also, there is a fine focus knob and a coarse focus knob. The coarse focus is for moving the objective lenses nearer/further away from the specimen while the fine focus is for fine-tuning the focus (usually when it is unclear). Use the coarse focus before the fine focus unless there is no need to zoom in on the specimen.

Finally, an illuminator might shine a light on the specimen so that you can see it more easily.