Hepatitis B is a viral infection that affects the liver, caused by the hepatitis B virus (HBV). Here are important aspects of hepatitis B:

1. Transmission: Hepatitis B virus is transmitted through contact with infectious blood, semen, and other body fluids. It can spread from mother to child during childbirth, through sexual contact, sharing of needles or syringes, and sometimes through sharing personal items such as razors or toothbrushes with an infected person.
2. Symptoms: Many people with hepatitis B may not have symptoms initially. When symptoms do occur, they can range from mild to severe and may include fever, fatigue, loss of appetite, nausea, abdominal discomfort, dark urine, joint pain, and jaundice (yellowing of the skin and eyes).
3. Chronic Infection: Unlike hepatitis A, hepatitis B can become a chronic infection. Chronic hepatitis B infection occurs when the virus persists in the body for longer than 6 months. Chronic infection can lead to serious health problems, such as liver cirrhosis, liver failure, or liver cancer.