The Toronto Star recently profiled Form-Mate, the last carbon paper manufacturer in Canada.
Like most people, I haven’t used carbon paper for many years. In fact, many younger people have probably never encountered this relic from our typewriter generation at all, or experienced the original, pre-email version of  “cc:” (“carbon copy”).  Before we had the “print button”, carbon paper was an amazing way to duplicate a document without having to retype it. For nearly a hundred years before digital duplication, carbon paper, along with competing technologies like mimeographs and ditto machines, were the primary means of duplicating an office document. [Note: if you haven’t encountered carbon paper before, see the description at the end of this post]
Like many technologies that were once ubiquitous, carbon paper is still used in various small niche markets.  The Economist reports that carbon paper is still used by New York police to make copies of evidence vouchers, prisoners in 44 US states must use carbon paper to make copies of outgoing letters (which they must type on specially manufactured electronic typewriters), and tattoo artists use carbon paper to transfer designs from paper to their customers’ skin before inking.  Carbon paper is also still used for some bank forms and small office receipt books.
Form-Mate attributes its survival to recognizing, even when established in 1978, that carbon paper was a declining business and niche markets would be the only ones to survive. Even so, carbon paper is headed inevitably for extinction.  As far as records managers and archivists go, this is probably just as well, given the challenges of storing and preserving carbon copies.  But it is also a reminder to look at our current technologies with an eye to their eventual obsolescence and disappearance.  The next time we need to call someone to repair a microfilm reader, recover data from a floppy disk, or – eventually – to repair a CD-ROM drive, we need to remember they might not be in business any more.  Anticipating declining technologies and planning for their obsolescence is easy to neglect, but technologies have to be revisited from time to time and format conversion projects need to be undertaken, otherwise sizeable portions of records could suddenly become very expensive to recover or be lost entirely.
Carbon paper:  A lightweight paper coated on one side with a dark waxy pigment that often contains carbon.
How does it work? A sheet of carbon paper is placed between an original and a second sheet of paper. As you write or type on the original, pressure deposits the ink from the reverse (back) side of the carbon paper onto the blank (second) sheet to create a carbon copy of the original. A single piece of carbon paper can be used repeatedly until the impression grows too light. If you aren’t careful when inserting and removing the carbon paper, you end up with black (or blue) ink on your hands.
Carbonless copy paper or NCR (No Carbon Required) paper
If you haven’t used carbon paper, you may have used carbonless copy paper or NCR paper which was developed to eliminate messy fingers and the hassle of inserting carbon paper between an original and second sheet. This paper also allows more than one copy to be produced at the same time.
How does it work? The back of the first sheet is coated with micro-encapsulated dye. The lowermost sheet is coated on the top surface with a clay that quickly reacts with the dye to form a permanent mark. Any intermediate sheets are coated with clay on top and dye on the bottom. Pressure from a typewriter, pen, or a dot matrix or impact printer causes the micro-capsules to break and spill their dye.
Each sheet in a business form made from NCR paper is usually a different colour to allow quick identification of the destination to which the original and each copy should be routed. For example, a purchase order may be a 3 page document with a white original (top) sheet to be issued to the supplier, a 2nd sheet (pink) to be retained by the buyer, and a 3rd sheet (green) to be sent to the Accounting Department for matching with an invoice in the future.