When you write a paper requiring MLA Style, you need to include in-text or parenthetical citations anytime you are using information that is not your own. This includes when you paraphrase or use direct quotations. The information you put in parentheses is the beginning of your bibliography entry and allows your teacher to quickly identify which source you are referring to. Generally, this means that the author's last name and page number go into parentheses at the end of your sentence. If you do not have an author's name, use whatever comes first in your bibliography entry.
A Visual Guide to Citing Online and Digital Sources in MLA by EasyBib and Glogster Edu
If you are writing a paper that requires Chicago Style, you are expected to use footnotes throughout any time you refer to information that is not your own idea. This includes when you paraphrase or use direct quotes. After you use someone's idea, you need to note it with a number after the punctuation. This number corresponds with a footnote at the bottom of the page (or at the end of your paper, if you are using endnotes). The first time you refer to a source, you must write out the full bibliographic information and page number. Subsequently, you use an abbreviated version.