Carbon copy

Before the development of photographic copiers, a carbon copy was the under-copy of a typed or written document placed over carbon paper and the under-copy sheet itself (not to be confused with the carbon print family of photographic reproduction processes). When copies of business letters were so produced, it was customary to use the acronym "CC" or "cc" before a colon and below the writer's signature to inform the principal recipient that carbon copies had been made and distributed to the parties listed after the colon. With the advent of word processors and e-mail, "cc" is used as a merely formal indication of the distribution of letters to secondary recipients. A sheet of carbon paper is placed between two or more sheets of paper. The pressure applied by the writing implement (pen, pencil, typewriter or impact printer) to the top sheet causes pigment from the carbon paper to reproduce the similar mark on the copy sheet(s). More than one copy can be made by stacking several sheets with carbon paper between each pair. Four or five copies is a practical limit. The top sheet is the original and each of the additional sheets is called a carbon copy. While carbon paper was invented by Pellegrino Turri in 1801, it was not widely used for copying until typewriters became common. Carbon copies were in wide use between the 1870s and 1980s, largely for administrative tasks. The use of carbon copies declined with the advent of photocopying and electronic document creation and distribution (word processing). Carbon copies are still sometimes used in special applications: for example, in manual receipt books which have a multiple-use sheet of carbon paper supplied, so that the user can keep an exact copy of each receipt issued, although even here carbonless copy paper is often used to the same effect. It is still common for a business letter to include, at the end, a list of names preceded by the abbreviation "CC", indicating that the named persons are to receive copies of the letter, even though carbon paper is no longer used to make the copies.