In 1943 , Abraham Maslow published a paper The Theory of Human Motivation in Psychological Review. His paper focussed on human beings inherent urge to attain fulfilment. That is to say what actually motivates a human being?!
Maslow classified human behaviour and ordered them in a priority list that is generally represented by a triangle in any diagram.
The segments are in particular order-
5. Psychological needs- food , water , warmth , shelter etc.
4. Safety needs – Security: Emotional & Physical
3.Social needs – Friendships, Family, intimacy etc
2. Self Esteem – Accomplishments to be appreciated by others
1. Self Actualisation – Self Realisation or achieving self goals.
Point1is the ultimate whereas point 5 is the most basic.