Every time you refer to information that is not your original conclusion and is not common knowledge, you must give credit to where that information comes from. You will typically note in parentheses the author's/authors' names and relevant page number. This allows you to give credit without wasting excessive page space or disrupting the flow of the paper.
The images below use MLA style, but APA functions the same way in this regard; it's just that APA in-text citations would also include a publication year.
If an article doesn't have an author, your Works Cited citation will start with the article title, and your in-text citation will reflect that. It's all about making it easy for your reader to make a one-to-one connection by just skimming down the left edge of the Works Cited page.