Question: What is the most common type of microscope?
About the article "Microscope", section "Optical".

Candidate passages:
A Student microscope is a low power, durable optical microscope typically sold in bulk for use in school science classes.
Although university science students use microscopes, the term typically refers to the type of instrument used in primary and secondary schools.
For most non-scientists, the only time a microscope was ever used was in a school science class, and so when many people picture a microscope, it is a student microscope that comes to mind. 
A microscope (from the , "mikrós", "small" and , "skopeîn", "to look" or "see") is an instrument 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.
Microscopic 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 which uses light to image the sample.
Other major types of microscopes are the electron microscope (both the transmission electron microscope and the scanning electron microscope) and the various types of scanning probe microscope. 
In botanical nomenclature, a "type" ("typus", "nomenclatural type"), "is that element to which the name of a taxon is permanently attached."
(article 7.1) In botany a type is either a specimen or an illustration.
A specimen is a real plant (or one or more parts of a plant or a lot of small plants), dead and kept safe, "curated", in a herbarium (or the equivalent for fungi).
Examples of where an illustration may serve as a type are (this is not an exclusive listing):  A detailed drawing, painting, etc., depicting the plant, from the early days of plant taxonomy.
A dried plant was difficult to transport and hard to keep safe for the future; many specimens from the early days of botany have since been lost or damaged.
Highly skilled botanical artists were sometimes employed by a botanist to make a faithful and detailed illustration.
Some such illustrations have become the best record and have been chosen to serve as the type of a taxon.
A detailed picture of something that can be seen only through a microscope.
A tiny "plant" on a microscope slide makes for a poor type: the microscope slide may be lost or damaged, or it may be very difficult to find the "plant" in question among whatever else is on the microscope slide.
An illustration makes for a much more reliable type (Art 37.5 of the "Vienna Code", 2006).
Note that a type does not determine the circumscription of the taxon.
For example, the common dandelion is a controversial taxon: some botanists consider it to consist of over a hundred species, and others regard it as a single species.
The type of the name "Taraxacum officinale" is the same whether the circumscription of the species includes all those small species ("Taraxacum officinale" is a "big" species) or whether the circumscription is limited to only one small species among the other hundred ("Taraxacum officinale" is a "small" species).
The name "Taraxacum officinale" is the same and the type of the name is the same, but the extent of what the name actually applies to varies greatly.
Setting the circumscription of a taxon is done by a taxonomist in a publication.
Miscellaneous notes:  Only a species or an infraspecific taxon can have a type of its own.
For most new taxa (published on or after 1 January 2007, article 37) at these ranks a type should not be an illustration.
A genus has the same type as that of one of its species (article 10).
A family has the same type as that of one of its genera (article 10).
The "ICN" provides a listing of the various kinds of type (article 9), the most important of which is the holotype.
These are  holotype  lectotype  isotype  syntype  paratype  neotype  epitype Note that the word "type" appears in botanical literature as a part of some older terms that have no status under the "ICN": for example a clonotype. 
An electron microscope uses a beam of electrons to illuminate a specimen and produce a magnified image.
Two common types of electron microscope are the scanning electron microscope (SEM) and transmission electron microscope (TEM). 
A total internal reflection fluorescence microscope (TIRFM) is a type of microscope with which a thin region of a specimen, usually less than 200 nm can be observed.