Imagination
Imagination in philosophy is the production of sensations, feelings and thoughts informing oneself. These experiences can be re-creations of past experiences, such as vivid memories with imagined changes, or completely invented and possibly fantastic scenes. Imagination helps apply knowledge to solve problems and is fundamental to integrating experience and the learning process. As a way of building theory, it is called "disciplined imagination". A way of training imagination is by listening to storytelling (narrative), in which the exactness of the chosen words is how it can "evoke worlds".One view of imagination links it with cognition,
seeing imagination as a cognitive process used in mental functioning. It is used — in the form of visual imagery — by clinicians in psychological treatment.
Imaginative thought may become associated with rational thought on the assumption that both activities involve cognitive processes that "underpin thinking about possibilities".The cognate term, "mental imagery" may be used in psychology to denote the process of reviving in the mind recollections of objects formerly given in sense perception. Since this use of the term conflicts with that of ordinary language, some psychologists have preferred to describe this process as "imaging" or "imagery" or to speak of it as "reproductive" as opposed to "productive" or "constructive" imagination. Constructive imagination is further divided into voluntary imagination driven by the lateral prefrontal cortex (LPFC) and involuntary imagination (LPFC-independent), such as REM sleep dreaming, daydreaming, hallucinations, and spontaneous insight. The voluntary types of imagination include integration of modifiers, and mental rotation. Imagined images, both novel and recalled, are seen with the "mind's eye".
Imagination, however, is not considered to be exclusively a cognitive activity because it is also linked to the body and place, particularly in that it also involves setting up relationships with materials and people, precluding the sense that imagination is locked away in the head.Imagination can be expressed through stories and writings such as fairy tales, fantasies,  science fiction, philosophy... Children often use such narratives and pretend play in order to exercise their imaginations. When children develop fantasy they play at two levels: first, they use role playing to act out what they have developed with their imagination, and at the second level they play again with their make-believe situation by acting as if what they have developed is an actual reality.

History
Imaginatio is the standard Latin translation of the Greek term phantasia. Aristotle in On the Soul considered phantasia (imagination) as the capacity for making mental images, and distinguished it from perception and from thinking. He held however that thought was always accompanied by an image.The notion of a "mind's eye" goes back at least to Cicero's reference to mentis oculi during his discussion of the orator's appropriate use of simile. Cicero observed that allusions to "the Syrtis of his patrimony" and "the Charybdis of his possessions" involved similes that were "too far-fetched". He advised the orator to, instead, just speak of "the rock" and "the gulf" (respectively) — on the grounds that "the eyes of the mind are more easily directed to those objects which we have seen, than to those which we have only heard".In medieval faculty psychology, the imagination was one of the inward wits along with memory and the sensus communis. It allowed the recombination of images, for example by combining perceptions of gold and mountain to obtain the idea of a golden mountain.The concept of "mind's eye" appeared in English in Chaucer's (c. 1387) Man of Law's Tale in his Canterbury Tales, in which he tells us that one of the three men dwelling in a castle was blind, and could only see with "the eyes of his mind"; namely, those eyes "with which all men see after they have become blind".Galileo used the imagination to conduct thought experiments, such as asking readers to imagine in what direction a stone released from a sling would fly.

Description
Imagination... is more important than knowledge. Knowledge is limited. Imagination encircles the world.
In Artificial intelligence see Generative artificial intelligence.
Imagination is an experimental partition of the mind used to develop theories and ideas based on functions. Taking objects from real perceptions, the imagination uses complex if-functions that involve both Semantic and Episodic memory to develop new or revised ideas. This part of the mind helps develop better and easier ways to accomplish old and new tasks.
In sociology, imagination is used to part ways with reality and have an understanding of social interactions derived from a perspective outside of society itself. This leads to the development of theories through questions that would not otherwise be asked. These experimental ideas can be safely conducted inside a virtual world and then, if the idea is probable and the function is true, the idea can be actualized in reality. 
Regarding the volunteer effort, imagination can be classified as:

involuntary (sleeping dreams and daydreams)
voluntary (the reproductive imagination, the creative imagination, the dream of perspective)

Psychology
Psychologists have studied imaginative thought, not only in its exotic form of creativity and artistic expression but also in its mundane form of everyday imagination. Ruth M.J. Byrne proposed that everyday imaginative thoughts about counterfactual alternatives to reality may be based on the same cognitive processes on which rational thoughts are based. Children can create imaginative alternatives to reality from their very early years. Cultural psychology views imagination as a higher mental function involved in a number of everyday activities both at the individual and collective level that enables people to manipulate complex meanings of both linguistic and iconic forms in the process of experiencing.
The phenomenology of imagination is discussed in The Imaginary: A Phenomenological Psychology of the Imagination (French: L'Imaginaire: Psychologie phénoménologique de l'imagination), also published under the title The Psychology of the Imagination, a 1940 book by Jean-Paul Sartre, in which he propounds his concept of the imagination and discusses what the existence of imagination shows about the nature of human consciousness.The imagination is also active in our perception of photographic images in order to make them appear real.

Memory
Memory and mental imagery, often seen as a part of the process of imagination, are affected by one another. "Images made by functional magnetic resonance imaging (fMRI) technology show that remembering and imagining sends blood to identical parts of the brain."Various psychological factors can influence the brain's ability to retain information as either long-term memories or short-term memories. Experiences stored as long-term memories are easier to recall, as they are ingrained deeper in the mind. Each of these types of memories require information to be taught in a specific manner so as to use specialized regions of the brain when that information is processed. This information can potentially help us to develop programs for young students that cultivate or further enhance their creative abilities. The neocortex and thalamus control the brain's imagination, along with many of the brain's other functions such as consciousness and abstract thought. Since imagination involves many different brain functions (emotions, memory, thoughts, etc.) portions of the brain where multiple functions occur—such as the thalamus and neocortex—are the main regions where imaginative processing has been documented.

Perception
Piaget posited that a person's perceptions depend on their world view. The world view is the result of arranging perceptions into existing imagery by imagination. Piaget cites the example of a child saying that the moon is following her when she walks around the village at night. Like this, perceptions are integrated into the world view so that they make sense. Imagination is needed to make sense of perceptions.

Brain activation
A study that used fMRI while subjects were asked to imagine precise visual figures, to mentally disassemble them, or mentally blend them, showed activity in the occipital, frontoparietal, posterior parietal, precuneus, and dorsolateral prefrontal regions of the subject's brains.

Evolution
Phylogenetic acquisition of imagination was a gradual process. The simplest form of imagination, REM-sleep dreaming, evolved in mammals with acquisition of REM sleep 140 million years ago. Spontaneous insight improved in primates with acquisition of the lateral prefrontal cortex 70 million years ago. After hominins split from the chimpanzee line 6 million years ago they further improved their imagination. Prefrontal analysis was acquired 3.3 million years ago when hominins started to manufacture Mode One stone tools. Progress in stone tools culture to Mode Two stone tools by 2 million years ago signifies remarkable improvement of prefrontal analysis. The most advanced mechanism of imagination, prefrontal synthesis, was likely acquired by humans around 70,000 years ago and resulted in behavioral modernity. This leap toward modern imagination has been characterized by paleoanthropologists as the "Cognitive revolution", "Upper Paleolithic Revolution", and the "Great Leap Forward".

Moral imagination
Moral imagination usually describes the mental capacity to find answers to ethical questions and dilemmas through the process of imagination and visualization. Different definitions of "moral imagination" can be found in the literature.The philosopher Mark Johnson described it as "[a]n ability to imaginatively discern various possibilities for acting in a given situation and to envision the potential help and harm that are likely to result from a given action."In one proposed example, Hitler's assassin Claus von Stauffenberg was said to have decided to dare to overthrow the Nazi regime as a result (among other factors) of a process of "moral imagination." His willingness to kill Hitler was less due to his compassion for his comrades, his family, or friends living at that time, but from thinking about the potential problems of later generations and people he did not know. In other words, through a process of “moral imagination” he developed empathy for "abstract" people (for example, Germans of later generations, people who were not yet alive).

See also
References
Further reading
BooksByrne, R. M. J. (2005). The Rational Imagination: How People Create Alternatives to Reality. Cambridge, MA: MIT Press
Fabiani, Paolo "The Philosophy of the Imagination in Vico and Malebranche". F.U.P. (Florence UP), Italian edition 2002, English edition 2009.
Salazar, Noel B. (2010) Envisioning Eden: Mobilizing imaginaries in tourism and beyond. Oxford: Berghahn.
Wilson, J. G. (2016). "Sartre and the Imagination: Top Shelf Magazines". Sexuality & Culture. 20 (4): 775–784. doi:10.1007/s12119-016-9358-x. S2CID 148101276.ArticlesSalazar, Noel B. (2020). On imagination and imaginaries, mobility and immobility: Seeing the forest for the trees. Culture & Psychology 1–10.
Salazar, Noel B. (2011). "The power of imagination in transnational mobilities". Identities: Global Studies in Culture and Power. 18 (6): 576–598. doi:10.1080/1070289X.2011.672859. S2CID 143420324.
Watkins, Mary: "Waking Dreams" [Harper Colophon Books, 1976] and "Invisible Guests - The Development of Imaginal Dialogues" [The Analytic Press, 1986]
Moss, Robert: "The Three "Only" Things: Tapping the Power of Dreams, Coincidence, and Imagination" [New World Library, September 10, 2007]
This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Imagination". Encyclopædia Britannica. Vol. 14 (11th ed.). Cambridge University Press. pp. 304–305.Three philosophers for whom imagination is a central concept are Kendall Walton, John Sallis and Richard Kearney. See in particular:

Kendall Walton, Mimesis as Make-Believe: On the Foundations of the Representational Arts.  Harvard University Press, 1990.  ISBN 0-674-57603-9 (pbk.).
John Sallis, Force of Imagination: The Sense of the Elemental (2000)
John Sallis, Spacings-Of Reason and Imagination. In Texts of Kant, Fichte, Hegel (1987)
Richard Kearney, The Wake of Imagination. Minneapolis: University of Minnesota Press (1988); 1st Paperback Edition- (ISBN 0-8166-1714-7)
Richard Kearney, "Poetics of Imagining: Modern to Post-modern." Fordham University Press (1998)

External links
 The dictionary definition of imagination at Wiktionary

 Media related to imagination at Wikimedia Commons
Imagination on In Our Time at the BBC
Imagination, Mental Imagery, Consciousness, and Cognition: Scientific, Philosophical and Historical Approaches
Two-Factor Imagination Scale at the Open Directory Project
"The neuroscience of imagination". TED-Ed.