Masking (in art)

In art, craft, and engineering, masking is the use of materials to protect areas from change, or to focus change on other areas. Masking can describe either the techniques and materials used to control the development of a work of art by protecting a desired area from change; or a phenomenon that (either intentionally or unintentionally) causes a sensation to be concealed from conscious attention. The term is derived from the word “mask”, in the sense that it hides the face from view.