1. Inline (I): Cylinders are arranged in a single row, all in a straight line along the engine's crankshaft.
2. V: Cylinders are arranged in two banks, forming a V-shape. The banks share a common crankshaft.
3. Flat/Horizontally Opposed (Boxer): Cylinders are arranged horizontally in two banks, opposite each other. Like the V-engine, they share a common crankshaft.