Needs can be categorised in two groups. The first group of needs such as eating, sleeping, drinking and so on which are indispensable. When any of these needs are missing for too long an intense sense of striving kicks in to fill these needs. These needs form the primary motive of human behaviour
The second group includes needs that are different from one person to another. One person might have a need for power while another person needs to submit. These needs are formed in childhood and once they become a part of someone it is difficult to change.