"A citation is the way you tell your readers that certain material in your work came from another source. It also gives your readers the information necessary to find that source again." -- From Plagiarism.org - What is Citation?
Basic Elements of a Citation for an Article
Example for a journal article citation in APA
Author: Wilhoit, Stephen
Title of article: Helping students avoid plagiarism.
Journal information: College Teaching, 1994, volume 42, issue 4, pages 161-65
APA Format: Author (Last name, Initial of first name). (Year of Publication). Title of article. Journal (Name of Journal in italics), Volume (Issue), and Pages.