Xerography or electrophotography is a dry photocopying technique. Its fundamental principle was invented by Hungarian physicist PÃ¡l SelÃ©nyi and based on SelÃ©nyi's publications Chester Carlson applied for and was awarded U.S. Patent 2,297,691 on October 6, 1942. The technique was originally called electrophotography.
A retrospective, generally, is a look back at events that took place, or works that were produced, in the past. As a noun, retrospective has specific meanings in medicine, software development, popular culture and the arts. It is applied as an adjective, synonymous with the term retroactive, to laws, standards, and awards.
All memory is in a sense 'functional' and is generally categorized into those that are 'implicit' (i.e., do not require conscious recollection, like knowing how to ski) and those that are 'explicit' (i.e., that involve conscious recollection of facts and experiences, like knowing where the best place to ski is).