A copyrighted work that is based on another work, but which includes additional creative ideas, for example a screenplay based on a book, a musical arrangement, or a translation of a book. A derivative work infringes the underlying work and so cannot be sold without the permission of the original copyright holder, while the original work’s copyright term is unexpired. However, the derivative work is in all other respects a work in its own right, with a copyright term calculated from its date of publication or creation.