Copyright law covers creating, owning, selling, and using creative and expressive works. Under U.S. law and in most other countries, creative work is automatically copyrighted upon creation, and the copyright generally belongs to the creator.
A copyright owner controls who can
A copyright owner can share some or all of those rights with others by transferring (assigning) ownership or granting licenses.
The copyright rights outlined above only apply to works that are
To qualify for copyright, works that fit into one of the categories above must also be "fixed in a tangible medium of expression." Almost anything counts as "fixed" - a drawing on a whiteboard or a file saved in a computer's memory qualifies. However, copyright doesn't protect completely unfixed works such as improvisational speeches or oral brainstorming.
A work also must include original creative expression to qualify for protection. The originality required is minimal, but "sweat of the brow" is insufficient. For example, writing out an alphabetical list of all Grammy winners may take a lot of work, but it doesn't contain any original creative expression. By contrast, if you add annotations and commentary to that list, you could own a copyright in the annotations and commentary.
Check out these resources for more on copyright.