You may have heard of “fair use.” It is discussed in the Copyright Act. Fair use is a concept that allows use of limited portions of a copyrighted work, without the permission of the copyright owner, for purposes such as scholarship, research, and criticism. Fair use does not mean that if you think it's fair that you should be able to use a work, it's okay. Rather, whether a particular use of copyrighted material is a fair use must be judged according to the four criteria in the Copyright Act:
For example, it's fine to quote from a book when writing about it, but it's not okay to reproduce the entire book.
Unfortunately, the four factors listed above do not always provide very clear guidance. Fair use must be determined on a case-by-case basis. Fair use can be tricky to define, so here are some links that do a pretty good job of explaining it.
Last Updated: 8/27/12