Hierarchy of needs refers to the concept in psychology that states that humans have different levels of needs that must be met in order for them to attain self-actualization. With that in mind, there are various synonyms that are used in place of hierarchy of needs. These synonyms include Maslow's hierarchy of needs, need hierarchy, motivational hierarchy, and needs theory. Psychologists and other scholars use these synonyms interchangeably when discussing the concept of hierarchy of needs. They all refer to the same idea, that humans have different needs that must be fulfilled in order for them to reach their full potential.