Some valuables are tangible: a Martin guitar, a ruby ring, an old engraving.  In the scholarly world, valuables are intangible; they come in the form of ideas: data from research, original insights, especially clear explanations and illustrations of difficult concepts and theories, and the like. On the one hand, no scholar wishes to have their ideas ignored. On the other hand, no academic wishes to have someone use their ideas, without receiving acknowledgement as their source.

Whenever we use—not just an entire sentence or more—but also specific words and/or phrase(s) from an author, we need to put the words in quotation marks and note their source.  Whenever we are relying on the ideas of others—not just the conclusions they have reached—but also their arguments, steps and/or research, we need to acknowledge the source(s) of the ideas we are using.  Plagiarism, the failure to document our sources, is a serious matter and the penalties for it can be quite stiff.

There are different styles of documentation, for example, MLA (Modern Language Association), APA (American Psychological Association), and Chicago. Before we begin working on our paper, we should check to see what style of documentation our professor requires, so that we can capture sources information in the proper format, while we are doing our research.   The writing centers at the University of Wisconsin-Madison and Utah Valley State provide information on the difference between various documentation styles and proper formatting in each style,  http://www.writing.wisc.edu/Handbook/Documentation.html  https://www.uvu.edu/library/guides/citations.html