Correction paper
A sheet of correction paper in a typewriter.
Correction paper, or correction film, its plastic based equivalent, is a tab of plastic with one side coated with white correction material. It is used to correct typing errors made when using a typewriter. When inserted between the paper and the typebar, and the ribbon select switched to 'stencil', i.e. inking turned off, the impression of the typebar presses the shape of the character into the film, which prints the white correction material onto the paper, hiding the erroneous character and preparing the document for the correct character.
See also