Neurons are specialized nerv cells. Thought to be the building blocks of our psyche. They come in various forms, which means they can be classified in various ways such as function or structure.
If sorted by structure (neuromorphology) then they are classified according to the number of branches that extend from the cell body. Such as unipolar, bipolar, and multipolar neurons. A unipolar cell is just the cell body, followed by the axon ending with denrites. A bipolar cell is best described by 1 cell body 2 axons and just 1 axon having dentrites at the end of it.
If classified by function then nerv cells can be categorized by their neurotransmitter receptors. Serotonin is a neurotransmitter along acetylcholine, dopamine, norepinephrine and others. For instance serotonin uptake inhibitors (SSRI) are used for treating depression.
Feldman, R. S., Meyer, J. S., & Quenzer, L. F. (1997). Principles of neuropsychopharmacology. Sinauer Associates.
Gray, H., & Lewis, W. H. (1918). Anatomy of the human body. Lea & Febiger. Philadephia, PA.