Maslow postulated that needs are arranged in a hierarchy in terms of their potency. Although all needs are instinctive, some are more powerful than others. The lower the need is in the pyramid, the more powerful it is. The higher the need is in the pyramid, the weaker and more distinctly human it is. The lower, or basic, needs on the pyramid are similar to those possessed by non-human animals, but only humans possess the higher needs.
The first four layers of the pyramid are what Maslow called "deficiency needs" or "D-needs:" the individual does not feel anything if they are met, but feels anxious if they are not met..... Needs beyond the D-needs are "growth needs," "being values," or "B-needs." When fulfilled, they do not go away; rather, they motivate further.
The base of the pyramid is formed by the physiological needs, including the biological requirements for food, water, air, and sleep.
Once the physiological needs are met, an individual can concentrate on the second level, the need for safety and security. Included here are the needs for structure, order, security, and predictability.
The third level is the need for love and belonging. Included here are the needs for friends and companions, a supportive family, identification with a group, and an intimate relationship.
The fourth level is the esteem needs. This group of needs requires both recognition from other people that results in feelings of prestige, acceptance, and status, and self-esteem that results in feelings of adequacy, competence, and confidence. Lack of satisfaction of the esteem needs results in discouragement and feelings of inferiority.
Finally, self-actualization sits at the apex of the original pyramid.