Prevention is usually defined as an action aimed at eradicating, eliminating or minimising the impact of a disease or disability, or aimed at slowing down the decline in functioning, health or quality of life associated with disease or disability. The focus of prevention is therefore on tackling causes and risk factors.

Different types of prevention are commonly distinguished. Primary prevention is action taken prior to the onset of a disease or the emergence of a need, with the aim of reducing or removing the possibility that the disease or need will ever occur. This could include action to inhibit the emergence of risk factors themselves, such as poor environmental, economic or social conditions. This is sometimes called primordial prevention and is focused on the broad health or social care determinants rather than individual exposure to them.

Secondary prevention is action which halts the progress of a disease or other condition at its incipient stage in order to prevent complications arising. Successful secondary prevention would then restore health or wellbeing by treating a disease or responding to a need before irreversible changes take place.

Tertiary prevention aims to reduce or limit the consequences of a disease or need, and to promote adjustment by an individual to irremediable conditions. It is therefore concerned with supporting individuals to cope with or manage their long-term health or social care problems or permanent impairments, in that way helping them to improve their ability to function independently and their quality of life.

Another type of prevention is sometimes distinguished: quaternary prevention is defined as protection from unnecessary medical or other care activity that could harm individuals or populations. An example in the health field would be over-medicalisation of what might be considered a ‘normal’ human condition or supplier-induced demand. In the social care area it could include creating unnecessary dependency by not empowering an individual to make independent decisions in their lives.