Carbon Paper has been around for since 1801 and has been used for many things, mostly making 1 or more copies of a document on a typewriter. It is rarely used today.

Currently it is often called Graphite Paper. Similar products have been made from various products that serve a particular purpose.

It works because the carbon paper has a coating of carbon graphite on one side. When pressure is applied to the other side of the paper, the carbon becomes transferred to whatever surface is against the carbon.

It is ideal for home or office use, great for art & craft projects. My most recent use has been for transferring a design to wood for etching. Just create the design on paper, then overlay a sheet of carbon paper on the wood (carbon side down), then the paper with the design over the carbon paper then trace the design. Lift the papers, and the design is on the wood.

Then just trace the transferred design with the etcher.