NCR paper (Carbonless paper)

Carbonless paper is a type of coated paper designed to transfer information written on the front onto sheets beneath.
Carbonless copy paper has micro-encapsulated dye or ink on the back side of the top sheet, and a clay coating on the front side of the bottom sheet. When pressure is applied (from writing or impact printing), the dye capsules rupture and react with the clay to form a permanent mark duplicating the markings made to the top sheet. Intermediary sheets, with clay on the front and dye capsules on the back, can be used to create multiple copies; this may be referred to as multipart stationery.
NCR, or Carbonless paper as it is often referred to, is a speciality coated paper designed to enable the transfer information between sheets. NCR paper can come in:
CF (coated front)
CB (coated back)
CFB (coated front back)