Whenever you quote, paraphrase, summarize, or refer to the work of another person, you are required to cite its source. Failure to cite the source of other's ideas and work is called plagiarism.
There are many formats and styles to use in citing sources. Teachers will usually provide guidelines in the citation style they want you to use in their classes and help can also be found in the library. The following websites may be also be used to get help in the citation of sources: