Before the development of photographic copiers, a carbon copy was the under-copy of a typed or written document placed over
carbon paper
Carbon paper (originally carbonic paper) consists of sheets of paper which create one or more copies simultaneously with the creation of an original document when inscribed by a typewriter or ballpoint pen.
History
In 1801, Pellegrino Tur ...
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.
Use
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.
The use of carbon copies declined with the advent of
photocopying
A photocopier (also called copier or copy machine, and formerly Xerox machine, the generic trademark) is a machine that makes copies of documents and other visual images onto paper or plastic film quickly and cheaply. Most modern photocopiers ...
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
Carbonless copy paper (CCP), non-carbon copy paper, or NCR paper (No Carbon Required, taken from the initials of its creator, National Cash Register) is a type of coated paper designed to transfer information written on the front onto sheets benea ...
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.
An alternative etymology is that "c:" was used for copy and "cc:" indicates the plural, just as "p." means page and "pp." means pages. This alternative etymology explains the frequent usage of "c:" when only one recipient is listed, while "cc:" is used for two or more recipients of the copies. This etymology can also explain why, even originally, "cc:" w