Neil Wilkonson at Writers Weekly presents a very helpful rundown of what Fair Use is:

As soon as your individual expression hits the page, as soon as it is reduced to a tangible medium of expression, that work, whether a book on wine, a poem, a textbook, a drawing, a song, an architectural design, or any number of other things belongs to you unless, of course, you transfer some or all of the rights granted to you under the U. S. Copyright Act Section 106 that provides:

[T]he owner of copyright under this title [Title 17 United States Code Annotated] has the exclusive rights to do and to authorize any of the following:
(1) to reproduce the copyrighted work in copies or phonorecords;

(2) to prepare derivative works based upon the copyrighted work;

(3) to distribute copies or phonorecords of the copyrighted work to the public by sale or other transfer of ownership, or by rental, lease, or lending;

(4) in the case of literary, musical, dramatic, and choreographic works, pantomimes, and motion pictures and other audiovisual works, to perform the copyrighted work publicly;

(5) 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, to display the copyrighted work publicly; and

(6) in the case of sound recordings, to perform the copyrighted work publicly by means of a digital audio transmission.

Know your rights! Read it all here.