This Constitutional provision simply states that Congress has the power.
To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.
Or, as the Stanford Copyright Guide ably explains,
Copyright protects works such as poetry, movies, CD-ROMs, video games, videos, plays, paintings, sheet music, recorded music performances, novels, software code, sculptures, photographs, choreography and architectural designs.
To qualify for copyright protection, a work must be "fixed in a tangible medium of expression." This means that the work must exist in some physical form for at least some period of time, no matter how brief. Virtually any form of expression will qualify as a tangible medium, including a computer's random access memory (RAM), the recording media that capture all radio and television broadcasts, and the scribbled notes on the back of an envelope that contain the basis for an impromptu speech.
In addition, the work must be original -- that is, independently created by the author. It doesn't matter if an author's creation is similar to existing works, or even if it is arguably lacking in quality, ingenuity or aesthetic merit. So long as the author toils without copying from someone else, the results are protected by copyright.
Finally, to receive copyright protection, a work must be the result of at least some creative effort on the part of its author. There is no hard and fast rule as to how much creativity is enough. As one example, a work must be more creative than a telephone book's white pages, which involve a straightforward alphabetical listing of telephone numbers rather than a creative selection of listings.
There are a number of links embedded throughout this libguide. The following are useful general guides that provide breadth and depth to copyright.