When you use the words, ideas, or creations of someone else, cite them. To make it easier to keep track of your sources, try a citation tool like RefWorks. Not sure how to properly format your citations? Citation styles (MLA, APA, Chicago) give you detailed guidelines. The citation style you use will depend on the discipline, journal, or course for which you are writing. See the Library's Citation and Style Guide for more help.
If you are writing about music, consider consulting the Music Citation guide.