Why is it necessary to show where words and ideas of others are used in your writing? When you use information from other authors in your writing, you must be honest about revealing your sources. To do this, various formal methods of acknowledging where you gathered information have been developed. These methods are called "documentation."
How documentation works
There are several specific styles of documentation, but all have the same idea: When you borrow another's information, you explicitly say in your paper what is borrowed and where it is from.
The documentation style you use depends on the disciplinary area of the subject. Your professor will tell you which style to use.
Web sites that can assist you in creating a citation in the proper format for Turabian, MLA, and APA are:
Other documentation styles can be found in the Documentation and Plagiarism Guide.