1.Basic understanding of bile duct pathology -- Development and anatomy of bile duct -- Bicarbonate umbrella and its disruption of the bile duct -- Biliary innate immunity and its disorder -- Cellular senescence and biliary disorders -- Vascular supply of the bile duct and ischemic cholangiopathy -- 2.Practical understanding of biliary diseases -- Immunopathology of bile duct lesions of primary biliary cirrhosis -- Natural and recurrent primary sclerosing cholangitis -- Recent progress of pathogenesis of IgG4-related sclerosing cholangitis -- Pathology and imaging of peribiliary cysts: recent progress -- Immunopathology of biliary atresia -- Cholangiolocellular carcinoma: Is it a subtype of cholangiocarcnoma or combined hepatocellular cholangiocarcioma ? -- Pathology of intrahepatic cholangocarcinoma: peripheral and perihilar subtypesIntraductal papillary neoplasm of bile duct -- Intraductal papillary cystic neoplasm of the gallbladder and ampulla of Vater -- Cystic and micropapillary neoplasm of peribiliary glands: Its perspective to cholangiocarcinogenesis -- Biliary intraepithelial neoplasia: cancer field for nodular sclerosing cholangiocarcinoma -- Intraductal papillary cystic neoplasm of the gallbladder and ampulla of Vater.