Memory. The retention and retrieval in the human mind of past experiences.
The function of remembering and its converse, forgetting, are normally adaptive. Learning, thought, and reasoning could not occur without remembering. On the other hand, forgetting has many functions, including time orientation by virtue of the tendency of memories to fade over time; adaptation to new learning by the loss or suppression of old patterns; and relief from the anxiety of painful experiences.
Some theorists believe memory is best described as a single storage and retrieval system. Others conceptualize a short-term memory where a limited amount of information (about five–nine items) can be held for a few seconds, after which it is either coded into a separate long-term system or lost. Organic evidence is adduced in favour of the two-system theory: persons who have suffered damage to an area of the brain called the hippocampus can retain short-term memory functions but are apparently unable to store any new long-term memory. Taken from Brittanica.com.