In 1943, Abraham Maslow's published an article "A Theory of Human Motivation", which appeared in Psychological Review.

This theory was about human motivation, based upon experiences with people.
Many psychology theories at that time were based upon animal behaviour.

The basis of Maslow's theory is that humans are motivated to satisfy needs.

According to Maslow, human needs fall into a hierarchy and certain lower needs need to be satisfied before higher needs can be satisfied.

Maslow's Hierarchy of Needs

Self-Actualization Esteem Needs Love Needs Safety Needs Physiological Needs

Maslow states that there are general types of needs (physiological, safety, love, and esteem) that must be satisfied before a person can act unselfishly. He called these needs "deficiency needs." As long as we are motivated to satisfy these cravings, we are moving towards self-actualization. Satisfying needs is healthy, while preventing gratification makes us sick or act selfishly.

According to Maslow's hierarchy, low-level needs such as physiological requirements and safety must be satisfied before higher level needs such as esteem can be fulfilled.

The diagram, sometimes called "Maslow's Triangle" or "Maslow's Pyramid", shows the hierarchy.

When a need at a lower level (towards the bottom of the triangle) is fulfilled, it no longer motivates, and a person will try to fulfil needs at the next higher level.

Physiological Needs

Physiological needs are those required to sustain life, such as:

Food
Water
Sleep

According to Maslow's theory, if these fundamental needs are not satisfied then a person will be motivated to satisfy them. A person will not try to fulfil higher needs, such as esteem until he satisfies the needs of basic existence.

Safety Needs

Once physiological needs are fulfilled, attention turns to safety and security in order to be free from the threat of physical and emotional harm. Such needs might be fulfilled by:

Living in a safe area
Financial Security

According to Maslow, if a person feels threatened, needs further up the pyramid will not receive attention until that need has been satisfied.

Love Needs

Once a person has met the lower level physiological and safety needs, a person will try to fulfil higher level needs. These needs include:

Love
Affection
Friendship
Social Acceptance

Esteem Needs

Once a person feels a sense of "belonging", the need to feel important arises. Esteem needs are those such as social status and recognition.

Self-respect
Achievement
Social Status
Recognition

(Maslow later refined his model to include a level between esteem needs and self actualization: the need for knowledge and aesthetics.)

Self-Actualization

Self-actualization is at the top of Maslow's hierarchy of needs. It is the quest of reaching full potential as a person.

Self-actualized people tend to have needs such as:

Truth
Justice
Wisdom
Meaning

According to Maslow, only a small percentage of the population reaches the level of self actualization.