Hepatitis B, known as viral hepatitis B, is a contagious disease caused by hepatitis B virus infection, with liver damage as the main manifestation. Hepatitis B virus can be transmitted through various routes, including blood, body fluids, mother-to-child transmission, sexual contact, and contact with broken skin and mucous membranes. China is a country with a high prevalence of hepatitis B. Vertical transmission from mother to child is the most important transmission route for hepatitis B in China, and it is estimated that 40% to 50% of infected people are infected by mother-to-child transmission. Hepatitis B virus may be present in the blood, semen and saliva of hepatitis B patients, and the higher the amount of virus, the more infectious it is. Between a husband and wife or a boyfriend and girlfriend, if one of them has hepatitis B, he or she may transmit it to the other through sexual contact, kissing, eating, and other close contacts in daily life, or a healthy person may accidentally contact the blood of a hepatitis B patient and become infected with the hepatitis B virus. It should be noted that although hepatitis B is contagious, normal daily contact between people infected with the hepatitis B virus, such as working together, holding hands, hugging, living in the same room, eating together, etc., will not cause transmission of the hepatitis B virus. In addition, hepatitis B vaccination is a reliable way to prevent hepatitis B. The hepatitis B vaccination can stimulate the body to produce hepatitis B surface antibody, thus protecting the body from hepatitis B virus infection. As a result, hepatitis B is a contagious disease that can be transmitted through blood and blood products, close contact, especially sexual contact, vertical transmission from mother to child, and medical transmission, etc. Infants and children and close contacts of hepatitis B who have not acquired antibodies should be vaccinated against hepatitis B in a timely manner to prevent hepatitis B virus infection. In addition, normal daily contact with people infected with hepatitis B virus will not cause transmission of hepatitis B virus.