Hepatitis B refers to a disease in which inflammation of the liver occurs due to the body's immune response when infected with the hepatitis B virus (HBV). Symptoms include fatigue, loss of appetite, nausea, and vomiting. Muscle pain and mild fever may occur, the color of urine may become darker, or in severe cases, jaundice may occur where the skin or eyes turn yellow. In fatal cases, it can even lead to death. Hepatitis B is transmitted through body fluids such as blood infected with the hepatitis B virus. A baby can be transmitted from a mother with hepatitis B at birth (vertical transmission), and can also be infected through sexual contact, blood transfusion, or reuse of a contaminated syringe. After the hepatitis B virus enters the blood through this route, it mainly settles in the liver cells. Our body mounts an immune response to eliminate this virus, which destroys the liver cells infected with the virus and causes inflammation in the liver.