The study of liver, gallbladder, biliary tree, and pancreas as well as diagnosis and treatment of their disorders. More than two billion people have been infected with hepatitis B virus at some point in their life, and approximately 350 million have become persistent carriers. Over two billion individuals have been infected with hepatitis B at some point and around 350 million people are persistent carriers. Hepatitis affects millions of individuals and is associated with several poor outcomes including liver transplant and liver cancer. Approximately 80% of liver cancers can be attributed to either hepatitis B or hepatitis C virus. With more wide spread implementation of vaccination and strict screening before blood transfusion, lower infection rates are expected in the future.