The term Application refers to applying one material to another or to put it on another surface. Thus, it is an act of placement, similar to when a mark is left behind by a paint brush, by an eyedropper loaded with dye, or a crayon, pencil, or pen. Additionally, application may refer to a use of a knowledge or theory in new and concrete situations.  This may include the application of such things as rules, methods, concepts, principles, laws, and theories. The term Application also might refer to a piece of computer software, which include also applications used in the field of art.