The term chronic disease applies to a group of diseases that tend to be long lasting and have persistent effects. This is opposed to acute diseases, which have a quick onset and are often brief, intense and/or severe.

Many factors influence how healthy we are. Some of these function on an individual level, for example, health behaviours or genetic make-up, while others function at a broader societal level, such as the availability of health services, vaccination programs or a clean and healthy environment. All these influencing factors are known collectively as determinants of health.