Self-esteem refers to the abstract idea of one's self. Most psychological ideas, because of their intangible natures, rely heavily on theory to help produce definitions. Theories of self-esteem are no exception, and most theories revolve around the thought that self-esteem is advantageous to high functioning, which is why people are motivated to maintain positive self-images.

Most psychologists regard self-esteem as an enduring characteristic. This basically means that it is a generally static state, however short-term it might be. Several factors can play roles in a person's momentary self-esteem. The self-image might also evolve as a person's perspectives or characteristics change — all funneling into a potential change of self-esteem. The terms "self-worth," "self-regard," "self-integrity" and other variations are commonly used interchangeably with "self-esteem."

Theories of self-esteem state that the ability to develop a healthy, positive image of oneself and others is inherently human. This theory suggests that all humans are born with a baseline self-esteem that is at a naturally high level. The amount of people who, admittedly or not, posses low self-esteem, however, supports evidence that, if this theory is correct, then something must go awry during development to cause a deterioration in how one thinks about oneself.

Just as there are conflicting theories of self-esteem, the reasons why a person's self-worth decreases is also subject of debate. Most professionals of psychology agree with three major sources of self-degradation. Self-punishment for breaking deeply instilled values, external negative influences or a lack of compassion are regarded as the top causes of low self-esteem.

Self-esteem has been defined as having a stable sense of personal worth or worthiness. This is in agreement with the static nature that most psychologists believe. Other psychologists believe that self-esteem is more competency-based and comes from being able to cope with life's challenges and considering oneself worth of being happy.

These are two of the many influential definitions of self-esteem, but many more definitions exist in the world of psychology that strive to accurately describe this elusive definition. The research community dedicated to psychology is constantly working toward advancements in the field, which is why some theories of self-esteem have become archaic in modern literature. A more evolved definition of self-esteem and self-confidence is that self-esteem comes from being mentally and emotionally able to handle new situations, even when the outcome is unknown.