There are (for the most part) two kinds of citations, and a few variations within those. Bibliographical citations describe information about a source, and are found in a bibliography, separate from an essay or project. In-text citations are notes about where information or a quotation can be found, and are included within the essay or project itself.
These are detailed, carefully formatted entries in a bibliography that give lots of details about a source and how to find it. It's generally best to use an online tool (such as NoodleTools) to format these citations; the rules are complicated, fussy, and they often change.
Whenever an essay writer includes a quotation or a piece of information that they did not come up with themselves, it is important to make a note about where the information was found. You are probably used to parenthetical citations at this point, which describe an author and page number, and are included right after a quotation. Narrative citations are used for sources that do not have a page number, and are written as part of the quote weaving before the quotation
Use these sorts of quotations when your quotation comes from a book, or other source with page numbers. They should look like this:
"When he was was nearly thirteen, my brother Jem got his arm badly broken at the elbow" (Lee 3).
Note that there is a period after the citation, so the period that would normally be after the word "elbow" in the quotation is left off. If the quotation ends with an exclamation point, question mark then the punctuation should be left in; if the quotation ends with a period, comma, colon, or semicolon, then that punctuation is left out.
When a source does not have page numbers (for instance: a website), then the information should be written in as part of the quote weaving. Before starting the quotation, mention the author's name (if you have it), the article title, and the company or organization that published the article. For instance:
In "The Courthouse Ring: Atticus Finch and the Limits of Southern Liberalism," published in The New Yorker, Malcolm Gladwell explains that Atticus does not ask the people Maycomb to ignore prejudice, but rather, "Finch does what lawyers for black men did in those days. He encourages them to swap one of their prejudices for another.”
Notice how the quote weaving mentions all three pieces of information: the author (Malcolm Gladwell), the article title, ("The Courthouse Ring: Atticus Finch and the Limits of Southern Liberalism"), and the magazine that published the article (The New Yorker).
If you are missing any of this information (for instance, you have an article on a website that does not list the author), do not worry: as long as you can get at least two of these pieces of information, your citation is complete.