Hepadnaviridae is a type of virus that primarily affects the liver. Hepatitis B virus (HBV) is the best-known member of the family. This virus can cause both acute and chronic liver disease. There are several synonyms for this word, including HBV, Hep B, and Hepadna virus. These synonyms can be used interchangeably, but they all refer to the same virus. Hepadnaviridae is a complex virus that has a unique replication cycle. It is primarily spread through blood and bodily fluids and can be prevented through vaccination. With appropriate medical care and preventive measures, the morbidity and mortality associated with this virus can be significantly reduced.