Once a source is incorporated into an essay, it is then cited on order to avoid plagiarism and to provide the reader with the necessary information about where the information originates from. How it is cited depends on the format (MLA, APA, Chicago Manual of Style) assigned by your professor.
Most writers know that quotes (using someone else’s exact words) must be cited, but any information that is taken from another source, even if it is paraphrased (put into different words), should be cited. The most important aspect of citing any source is making it clear that the information being presented is coming from another source by giving the full name of the author or organization behind the information.
Quotes: Anytime the exact wording of an original source/author is used, no matter how short or long the wording is, it must be placed in quotation marks and attributed to the original source.
Paraphrases: A paraphrase involves restating original information into your own words. The key to a successful paraphrase is to change both the wording used and the order, or structure, or the sentence.
Statistics and data: Studies often result in statistics. This type of data must be cited by providing the name of the person or agency responsible for generating the statistic(s).
Studies: The findings and/or interpretations of studies must be attributed by citing the primary researcher(s) responsible for the study.
Arguments and ideas: Anytime you, as the writer, are providing a specific argument or idea made by someone else, this needs to be cited.
Summaries: A summary is a condensed version of another work put into your own words. In this sense, it’s like a paraphrase, but summaries generally occur when using longer or complete sources. For example, a writer may summarize an entire essay or study, a section or chapter of a book, or even an entire book. When summarizing, be sure to cite all information to the original author and cite specific information (such as stats) or quotes with full citations.