Mental health is a term used to describe either a level of cognitive or emotional well-being or an absence of a mental disorder. From perspectives of the discipline of positive psychology or holism mental health may include an individual's ability to enjoy life and procure a balance between life activities and efforts to achieve psychological resilience. Mental health is an expression of our emotions and signifies a successful adaptation to a range of demands.

The World Health Organization defines mental health as "a state of well-being in which the individual realizes his or her own abilities, can cope with the normal stresses of life, can work productively and fruitfully, and is able to make a contribution to his or her community". It was previously stated that there was no one "official" definition of mental health. Cultural differences, subjective assessments, and competing professional theories all affect how "mental health" is defined.

Most recently, the field of Global Mental Health has emerged, which has been defined as 'the area of study, research and practice that places a priority on improving mental health and achieving equity in mental health for all people worldwide'.