Copyright law also protects individuals wanting to reproduce parts of a work for nonprofit purposes. Using a small portion of a work for scholarship or criticism is generally seen as fair use and does not require getting permission from the copyright holder. Whether use of a work is considered fair depends on
- the nature of the original work
- how the copy is to be used
- what portion of the original is copied
- the possible effect reproducing the work will have on the value of or market for the work
If you photocopy a few measures of music to include in your paper, that's fair use. However, if you make enough copies of the sheet music to give to everyone in the school choir, you are stealing income the publisher should have received from the sale of multiple copies and you have violated copyright.
Copyright laws are complicated and fair use is not always clear-cut. It’s better to err on the side of caution than to face a copyright infringement suit.