Knowledge of cross‐sectional anatomy of the liver is essential for the determination of localization of disease processes and for their management. Functional anatomy of the liver describes the functional segments of the liver on the basis of the anatomy of hepatic vessels and bile ducts. The hepatic arteries, hepatic veins, portal veins, and bile ducts demonstrate frequent variations which may affect surgical procedures in liver transplantations and liver resections. One of the most common normal variations of the segments of the liver is Riedel's lobe, which is characterized by the vertical elongation of the right lobe and it appears as a downward tongue‐like projection of segment V and VI. Another common variation is the hypoplasia or aplasia of segments of the liver. The interposition of the colon between the morphologically normal liver and the chest wall is yet another variation.