Maslow’s hierarchy of needs was created by American psychologist Abraham Maslow in 1943. Maslow suggested that human needs could be put into five levels.

Hierarchy needs levels (pyramid)  
The levels are in order of importance.
 Basic needs.  These include things such as breathing, food, water, and sleep.
Safety needs. This includes things such as feeling physically safe in your environment. It includes feeling healthy. It includes feeling that you have enough money and supplies to keep you alive and well. 
Social belonging. People need to feel love, and they need to feel that they belong in society. Partners could include husbands, wives, girlfriends, or boyfriends. 
Self-esteem. To have esteem, you need to be confident in yourself.  Also, you feel like others think that you are important. 
Self-actualization. This complicated idea is expressed as “What a man can be, he must be”. This level is about a person having the opportunity to use their talent, and a chance to go where those talents might lead.
Transcendence. Giving oneself to something beyond oneself—for example, in altruism or spirituality. This was a later addition to his ideas.

Maslow says that these needs cause us to want or desire certain things. He says that there are many other things that influence our behavior. Just because we may want something, does not mean we will try to get it. There could be something else in the way that causes us to act differently.

Physiological Needs 
The physiological level of Maslow's hierarchy includes basic human needs. These include water, breathing, food, and sleep. The physiological level contains the simplest needs. They are the most straightforward needs in the entire hierarchy. The human body tries to stay balanced inside. When a person is missing a physiological need, the body will naturally want the missing need. 

In simple creatures such as rodents, physiological needs may be the only needs that have to be met. However, in humans, this is only the base of the hierarchy. After physiological needs are met, there are four higher levels in the hierarchy. People are often not aware when their physiological needs are being met. However, when these needs are not met it becomes very obvious. For example, most humans do not think about each inhale and exhale they take. This satisfies their need to breathe. However, if the oxygen supply were cut off, all people would immediately become aware of the need to breathe. Physiological needs are important from the time a person is born and throughout their entire life.

Safety Needs 
The safety level of Maslow's hierarchy includes varying levels of safety. These include safety of the self, family, resources, jobs, health, and life. Both children and adults are very aware of their safety needs. Needs of safety are just as important as physiological needs. However, these needs deal more with the mind. They include having a sense of safety in the world. Every person’s sense of safety is different depending where they live.

Adults, much like children, prefer the world to be organized. This ensures a level of safety. However, some adults are too focused on organization. People may also attempt to control the world around them in all ways possible. Adults may have their safety needs met in a different way than children. Adults can feel that the money they earn from their job allows them to feel safe. This is because there is no need for financial worry when earning a steady income.

Love and belonging (social needs) 
The love/belonging level of Maslow's hierarchy deals with various social needs. These include a need for friendship, family, and other types of group inclusion. Love/belonging also refers to personal relationships. These include romantic relationships. It is crucial that the physiological and safety needs of a person are met first. Then they can develop needs of love and belonging. Once basic needs are met, then a person can focus on their social needs. These needs change throughout the human lifespan. 

If belonging needs are not met then a person may feel depressed. The field of psychology focuses on this level of the hierarchy. In modern society, many people suffer because their needs of love and belonging are not met. This level also deals with sexual and intimate needs. Sex may or may not be part of this level of need. It can be considered necessary for love. Or it can be looked at as strictly physiological.

Esteem Needs 
The esteem level is about how people need to feel that they play a part in the world. People want to feel that they have accomplished things that are valuable and important. They also want to feel independent, meaning that they can do things for themselves and do not need to depend on anybody else.

Self-actualization Needs 
We cannot be truly happy without becoming everything that we want to become. People have different things that they might want in their life that go along with this level. These needs do not show themselves until all of the needs in previous levels have been taken care of. For example, if a person is worrying about feeding themselves and needs to think about their physiological needs, then they will not be thinking about self-actualization and their life goals. Making sure they have food and a home is more important. Someone only reaches the self-actualization level once all the other levels are fulfilled.

Exceptions 
Maslow explains that there are exceptions to the hierarchy. The most important are:

One exception is that for some people, self-esteem is more important than love and belonging. This is the switch that happens most often. It happens because some people think that having self-esteem makes you strong, powerful, and respected. They also think that other people are more likely to love someone that has those qualities.
The second exception is people who are naturally very creative. Some people value creativity over everything else. Expressing your creativity would usually fall into the self-actualization level, which is the last level on the hierarchy. This means that all of the other basic needs should be met before people think about expressing their creativity. But for some people, creativity is very important and that is what they will desire, even if their needs on the lower level are not met.
The third exception is for people who have lived their whole life worrying about the basic needs. If you are going to be worried about having enough food and shelter, then the higher levels (such as esteem and self-actualization) will disappear.
The fourth exception is about psychopaths. Maslow describes these  as people that were not given enough love when they were babies in the first few months of life. When this happens, a person could lose the desire for love altogether and not think that it is important anymore. Psychopaths cannot give or receive love and have lost the ability to feel it. For this type of people, the love and belonging level would not exist.

Criticism 
Maslow’s hierarchy suggests that all human behavior is motivated. However, this may not be true. Some human behavior may simply be reflexive. Maslow holds a biased opinion on the definition of self-actualization. Each individual may have a different opinion of what it means to self-actualize. Maslow believed that people who self-actualized had great characteristics. He believed these made them natural leaders and incredible people. This makes the goal of self-actualization nearly impossible for the average person. Maslow’s theory states that lower level needs must be met in order to meet needs in the higher levels. 

However, this is not always the case. It is possible for people who suffer from poverty and hunger to still feel love and belonging. Therefore, higher level needs can be met in some cases even if lower levels needs are neglected. Some theorists argue that the levels of the hierarchy are out of order in terms of necessity. Some needs that are higher in the hierarchy may actually appear and become important early in an infant or child’s life. Maslow’s hierarchy is hard to prove scientifically. It cannot be proved false easily. There may not be enough hard, scientific evidence to fully support Maslow’s hierarchy.

Evidence 
An extensive review of research based on Maslow's theory found little evidence for the ranking of needs that Maslow described, or for the existence of a definite hierarchy at all.

The order in which the hierarchy is arranged has been criticized as being ethnocentric. In turn, Hofstede's work has been criticized by others. 

Maslow's hierarchy does not tackle the difference between the social and intellectual needs of those raised in individualistic societies and those raised in collectivist societies. 

The needs and drives of those in individualistic societies may be more self-centered than those in collectivist societies. They may focus on improving themselves. In collectivist societies, the needs of acceptance and community may outweigh the needs for freedom and individuality.

References 

 A Theory of Human Motivation. In Psychological Review. 1943, Vol. 50 #4, pages 370–396; A Theory of Human Motivation – online version at the University of York.

Maslow was 5'10
Psychology