What is copyright?
The preamble for U.S. copyright law states the goal of copyright 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." U.S. Const., art. I, § 8, cl. 8.
With some exceptions, copyright protection applies to "original works of authorship fixed in any tangible medium of expression" (17 U.S. Code §102a). Note the words "original" and "fixed" - it needs to be both things. For example, if you have an original idea for a poem but have not expressed it in a tangible medium, that poem is not protected by copyright.
Section 106 of the 1976 Copyright Act gives the owner of the copyright the exclusive right to do and authorize others to
- reproduce the work in copies or phonorecords
- prepare derivative works based upon the work
- distribute copies or phonorecords of the work to the public by sale or other transfer of ownership, or by rental, lease, or lending
- perform the work publicly, in the case of literary, musical, dramatic, and choreographic works, pantomimes, and motion pictures and other audiovisual works
- display the work publicly, in the case of literary, musical, dramatic, and choreographic works, pantomimes, and pictorial, graphic, or sculptural works, including the individual images of a motion picture or other audiovisual work
- perform the work publicly (in the case of sound recordings*) by means of a digital audio transmission
This list is from Copyright Basics (2012) available at https://www.copyright.gov/circs/circ01.pdf