In the U.S., copyright is first and foremost a federal law passed by Congress under authority given it by the Constitution, where it says that Congress is allowed to pass laws to (among other things) promote the progress of science and the useful arts by securing for limited time to authors and inventors the exclusive right to their respective writing and discoveries. This authorization allows Congress to adopt both copyright laws which protect creative expression, and patent laws, which are very different and provide exclusive rights in inventions. In this unit we will examine what is copyright and how it happens.