Works in the public domain are those whose intellectual property rights have expired, been forfeited, or are inapplicable. Examples include the works of Shakespeare and Beethoven, most of the early silent films, the formulae of Newtonian physics, and the patents on powered flight. The term is not normally applied to situations when the creator of a work retains residual rights, in which case use of the work is referred to as "under license" or with permission.