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.
For other uses, see Introspection (disambiguation). Introspection is the examination of one's own conscious thoughts and feelings. In psychology the process of introspection relies exclusively on observation of one's mental state, while in a spiritual context it may refer to the examination of one's soul. Introspection is closely related to human self-reflection and is contrasted with external observation.