This document summarizes different classes of diuretic drugs, including their mechanisms of action and examples. It discusses loop diuretics that inhibit sodium reabsorption in the ascending loop of Henle; thiazide diuretics that inhibit sodium transporters in the distal convoluted tubule; carbonic anhydrase inhibitors that suppress carbon dioxide reabsorption in the kidney; potassium-sparing diuretics that decrease sodium transport in the collecting tubule; and osmotic diuretics that increase osmotic pressure in the proximal tubule to prevent water reabsorption. Examples are provided for common drugs in each class, along with their sites and mechanisms of diuretic action.