Insight can be used with several related meanings:

• a piece of information
• the act or result of apprehending the inner nature of things or of seeing intuitively
• the power of acute observation and deduction, penetration, discernment, perception
• introspection

An insight that manifests itself suddenly, such as understanding how to solve a difficult problem, is called with a German word Aha-Erlebnis. The term was coined by the German psychologist and theoretical linguist Karl Bühler. It is also known as an epiphany.

In psychology and psychiatry

In psychology and psychiatry, insight is the ability to recognize one's own mental illness. Anosognosia is the total lack of insight into one's own mental illness. Problem solving behavior requiring insight is the subject of insight phenomenology.

An insight is the derivation of a rule which links cause with effect. The mind is a model of the universe built up from insights. Thoughts of the mind fall into 2 categories:

1) Analysis of past experience with the purpose of gaining insight for use within this model at a later date

2) Simulations of future scenarios using existing insights in the mind model in order to predict outcomes

A mature mind has assimilated many insights and understands cause and effect. When insight is not subordinate to a validation discipline like the 'scientific method', fallacious thinking can result in a confused mind.

Intuition ,which is often described in the popular literature as an alternative thought process, is merely another manifestation of insight. In this process ,multiple bits of seemingly unrelated data are linked together and a a hypothesis or plan of action is generated.Usually this process is generated in a novel situation. Such a circumstance links data which had hitherto seemed unrelated. . The categories and analytical process, however, are not distinct from any other form of insight. The only difference is the degree of novelty of the stimulus. To form an insight the frontal lobe searches through the temporal lobes in search of the data bits. It has been hypothesized that the apparently intuitive mode uses a right temporal search. The majority of insights are derived from the left temporal lobe.

In religion

In religion insight is seen as divine intervention from God, from the simple form of coming to believe to the extreme of miracles.

In Buddhism, the Pali word for "insight" is "vipassana".

In business

Bradley (2007) points out a recent development in the world of business. There has been the emergence of new departments in corporations which carry the word “Insight” in their titles. We have “Customer Insight Departments”, Insight Management Unit, Consumer Insight and so on. This extends to the job titles of executives working in those areas. One reason for this development was a realisation that the emphasis of results from individual research projects needed to be shifted to a wider understanding of the dynamics operating in the full market place. Another reason was the impact of information technology. Progress in technology gave way to the availability of masses of information found in databases. The advantages of Insight Management are numerous. By making use of all existing information, there is less need to consult customers, thereby minimising unnecessary contact and costs.