Hepatitis B virus (HBV) is a virus that primarily affects the liver, leading to inflammation and potential long-term health issues. It spreads through contact with infected bodily fluids, such as blood, semen, or vaginal secretions. Common ways of transmission include sharing needles, unprotected sex, and from mother to baby during childbirth. Many people with HBV may not show symptoms, but it can cause serious liver problems, including cirrhosis and liver cancer. Vaccination is available and highly effective in preventing HBV infection, making it an important public health measure to protect individuals and communities from this virus.