HBV, or Hepatitis B virus, is a virus that primarily affects the liver, leading to inflammation and potential long-term health issues. It is transmitted through contact with infectious body fluids, such as blood, semen, or vaginal secretions. Common modes of transmission include unprotected sexual contact, sharing needles, and from mother to child during childbirth. Infection with HBV can be acute or chronic. Acute infections may resolve on their own, while chronic infections can lead to serious complications, including liver cirrhosis and liver cancer. Vaccination is available and effective in preventing HBV infection, making it a crucial public health measure.