Correction paper, or correction film, its plastic based equivalent, is a tab of plastic

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

 with one side coated

Coated paper

Coated paper is paper which has been coated by a compound to impart certain qualities to the paper, including weight, surface gloss, smoothness or reduced ink absorbency. Kaolinite or calcium carbonate are used to coat paper for high quality printing used in packaging industry and in magazines...

 with white correction material. It is used to correct typing errors made when using a typewriter

Typewriter

A typewriter is a mechanical or electromechanical device with keys that, when pressed, cause characters to be printed on a medium, usually paper. Typically one character is printed per keypress, and the machine prints the characters by making ink impressions of type elements similar to the pieces...

. When inserted between the paper

Paper

Paper is a thin material mainly used for writing upon, printing upon, drawing or for packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....

 and the typebar

Typebar

A typebar is an 'arm' inside a typewriter with a character on the end of it. There are generally two characters per typebar, one which will be printed if the corresponding key is struck by itself, the other of which will be printed if the corresponding key is struck while the shift key is depressed...

, 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

Glyph

A glyph is an element of writing: an individual mark on a written medium that contributes to the meaning of what is written. A glyph is made up of one or more graphemes....

 and preparing the document

Document

The term document has multiple meanings in ordinary language and in scholarship. WordNet 3.1. lists four meanings :* document, written document, papers...

for the correct character.