Abraham Maslow

Abraham (Harold) Maslow was an American psycohologiss. He stated a hierarchy of human needs and is considered the father of humanistic psychology.
Maslow hierarchy pyramide:

Maslow has set up a hierarchy of five levels of basic needs. In the levels of the five basic needs, the person does not feel the second need until the demands of the first have been satisfied. Maslow's basic needs are as follows:
Physiological Needs
These are biological needs. They consist of needs for oxygen, food, water, and a relatively constant body temperature. They are the strongest needs because if a person were doesn’t have the needs,person searchs for satisfaction.
Safety Needs
When all physiological needs are satisfied, the needs for security can become active. Adults aren’t aware of their security needs except in times of emergency. Children often display the signs of insecurity and the need to be safe.
Needs of Love, Affection and Belongingness
When the needs for safety and for physiological well-being are satisfied, the next class of needs for love, affection and belongingness can emerge. Maslow states that people seek to overcome feelings of loneliness and alienation. This involves both giving and receiving love, affection and the sense of belonging.
Needs for Esteem
When the first three classes of needs are satisfied, the needs for esteem can become dominant. These involve needs for both self-esteem and for the esteem a person gets from others. Humans have a need for a stable, firmly based, high level of self-respect, and respect from others. When these needs are satisfied, the person feels self-confident and valuable as a person in the world. When these needs are frustrated, the person feels weak, helpless and worthless.
Needs for Self-Actualization
When all of the needs are satisfied,the needs for self-actualization activated. Maslow describes self-actualization as a person's need to be and do that which the person was "born to do”.For example, a musician born to play music.

With respect to Maslows pyramid,for example if person is lack of 3,4 and 5th steps we can know that what is missing in person’s life.
Maslow’s pyramid is also used in management.He is called as the Father of Enlightened management.

references:http://honolulu.hawaii.edu/intranet/committees/FacDevCom/guidebk/teachtip/maslow.htm

http://ourworld.compuserve.com/homepages/hstein/hoff2.htm

http://en.wikipedia.org/wiki/Abraham_Maslow