Liver cells are like leaves of a tree; and bile ducts are like branches and trunks from thin to thick. Anatomically, they are divided into intrahepatic bile ducts (including capillary bile ducts, intersegmental bile ducts and interlobular bile ducts); and extrahepatic bile ducts (including right and left hepatic ducts, common hepatic duct, common bile duct and gallbladder). If the tumor originates from hepatocytes (like growing on leaves), we call it hepatocellular carcinoma; if the tumor originates from bile duct cells within the liver (like branches above the left and right tree trunks), it is called intrahepatic bile duct cell carcinoma; if it originates from both, it becomes mixed liver cancer. The three are collectively called primary hepatocellular carcinoma. If the tumor originates from the extrahepatic bile ducts (excluding the gallbladder) below the left and right hepatic ducts, we call it cholangiocarcinoma. Those originating from the gallbladder are called gallbladder cancer.