An important thing to consider also is something called Fair Use ...
In determining whether the use made of a work in any particular case is a fair use the factors to be considered shall include.
(1) the purpose and character of the use, including whether such use is of a commercial nature or is for nonprofit educational purposes;
(2) the nature of the copyrighted work;
(3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole; and
(4) the effect of the use upon the potential market for or value of the copyrighted work.