This chapter aims to cover important classifications in pharmacology with the help of flowcharts. Cholinergic drugs, topical drugs for glaucoma, anticholinergic drugs, adrenergic drugs according to therapeutic use, α-adrenergic blocking drugs, beta-blockers, drugs for migraine, antirheumatoid drugs, drugs for gout, drugs for bronchial asthma, thyroid inhibitors, insulins, skeletal muscle relaxants, corticosteroids, topical steroids, general anesthetics, antidiabetic drugs other than insulin, uterine relaxants, antiepileptic drugs, opioid analgesics and antagonists, antihypertensive drugs, etc. are some drugs whose classifications are given in this chapter.