Immunity - GCSE Biology Definition

Immunity is the body's ability to protect itself from harmful pathogens and diseases. It works through the immune system, which is like a defence army made up of cells and proteins. When pathogens, such as bacteria and viruses, enter the body, the immune system recognises them as invaders and works to destroy them. Sometimes, the body is exposed to a pathogen but doesn't get sick because the immune system fights it off quickly. Vaccinations can also help by teaching the immune system to recognise and attack certain pathogens before they cause disease. Immunity can be either natural, coming from the body’s own defences, or acquired, when it's developed through exposure or vaccines.