What is a carbon copy notation in a letter?

The carbon copy notation of a letter, indicated with "cc:" and followed by a name or names, shows recipients who else received the same correspondence. It is included after the closing, signature and postscript.

Carbon copy recipients are visible on both written correspondence and email, while blind carbon copy recipients are hidden. On a written letter, the "bcc:" notation may be present but no names follow.

The term carbon copy comes from the method for copying letters when typewriters were used to write them. A piece of carbon paper was inserted between two sheets of paper so a letter could be duplicated easily while it was typed.