The format presented in the Atlas of the Liver series focuses on presentations of photomicrographs, tables and charts supplemented by concise explanations which supplement research articles, reviews and textbooks. More is presented in this edition of the Atlas of the Liver about the causes and effects of fat deposition in the liver than in previous volumes. The authors of the new chapter discuss nonalcoholic fatty liver disease further emphasizing the important roles of fat in the liver. Fat in the liver has long been recognized as a constant finding in obese patients, diabetic patients, and a regular consequence of alcohol-induced liver injury. Excellent sections on bilirubin metabolism, and the management of major complications of liver disease including ascites, spontaneous bacterial peritonitis, hepatic encephalopathy and portal hypertension are presented. The characteristics and natural histories of acute viral hepatitis and the important roles of vaccination in the prevention of hepatitis A and hepatitis B are well discussed.