Hepatitis B is a virus that infects and attacks the liver. Many people are exposed to the virus at some time in their lives and are able to fight the acute infection off completely with no complications or only mild, temporary symptoms. However, some people are unable to eradicate the virus and become chronically infected. They have the hepatitis B virus in the body for the rest of their lives. This latter group of people is called chronic hepatitis B carriers and can spread the virus to other people. In addition, over many years, the chronic infection may damage the liver and lead to liver failure. In certain circumstances, the virus can also lead to liver cancer.