Hepatitis B is an infection of the liver caused by a virus.
Hepatitis B does not always have symptoms. Possible symptoms of an infection include a high temperature, feeling sick, diarrhoea and tummy pain.
Hepatitis B sometimes gets better without treatment. It if lasts a long time, you may need medicines to keep the virus under control.
Hepatitis B is spread in blood and bodily fluids. Ways it can be spread include having sex without a condom and sharing needles.
There is a vaccine that can help prevent hepatitis B. The vaccine is offered on the NHS to all babies born in the UK and some people at high risk.