Hepatitis B is an infectious illness caused by hepatitis B virus (HBV) which infects the liver of hominoidea, including humans, and causes an inflammation called hepatitis. Originally known as “serum hepatitis”, the disease has caused epidemics in parts of Asia and Africa, and it is endemic in China.About a quarter of the world’s population, more than 2 billion people, have been infected with the hepatitis B virus. This includes 350 million chronic carriers of the virus. Transmission of hepatitis B virus results from exposure to infectious blood or body fluids such as semen and vaginal fluids, while viral DNA has been detected in the saliva, tears, and urine of chronic carriers with high titer DNA in serum. Perinatal infection is a major route of infection in endemic (mainly developing) countries.Other risk factors for developing HBV infection include working in a health care setting, transfusions, and dialysis, acupuncture, tattooing, extended overseas travel and residence in an institution. However, Hepatitis B viruses cannot be spread by casual contact, such as holding hands, sharing eating utensils or drinking glasses, breast-feeding, kissing, hugging, coughing, or sneezing.