Place commas, periods, exclamation marks, and question marks inside quotation marks; all other punctuation marks are placed outside quotation marks.
Use double quotation marks when:
Providing direct quotations of less than forty words (for quotes with more than forty words, use block quotations). If there are quotation marks within a quote of less than forty words, change those to single quotation marks.
Referring to a letter, word, phrase, or sentence as a linguistic example of itself: the letter "p"; the singular "they"; he wrote over and over "all work and no play makes Jack a dull boy."
First introducing a word or phrase ironically, as slang, or newly coined: I was not what you would call a "normal" teenager. The study produced what I will refer to as "alpha-particles."
Mentioning the title of a periodical or book chapter: In chapter one, "The Boy Who Lived"...; Maniotes and Kuhlthau's (2014) article, "Making the Shift: From Traditional Research Assignments to Guiding Inquiry Learning," describes...
Within double quotation marks, convert double quotation marks to single quotation marks: She told me, "It seems like everyone is always looking down at their phones, but, as Plato said, 'It is clear to everyone that astronomy at all events compels the soul to look upwards, and draws it from the things of this world to the other' (ca. 375 B.C.E./1908)."
Do not use quotation marks when:
Highlighting a key term or phrase for which a definition will be provided; instead, use italics: the principle of reciprocity can be defined as...
The meaning of a number is clear: Alex wears the number 13 jersey.
Semicolon
Use to separate lists containing commas: The American flag is red, white, and blue; rectangular, flat, and thin; and slack, waving, or fluttering.
Use to separate multiple in-text citations rather than having sets of parentheses next to each other: (n1 = 33; n2 = 11; Fu & Ginsburg, 2020).
Serial Comma
Also known as an "Oxford comma."
Include a comma after the second-to-last item in a series of three or more elements: The three branches of government are executive, legislative, and judiciary.
Spacing
One space is usually added after a punctuation mark at the end of a sentence; however, some instructors and publishers prefer two.
Do not add spaces after internal periods in abbreviations: e.g., U.S.A., i.e., F.D.R.
Square Brackets
Use to enclose text within parentheses: (The results for the control group [n=5] are illustrated in Figure 6); but use commas when it is a year: (Gregory, 2020, concluded that . . . ).
Use to insert text into a quotation for clarification: The author states, "[Eloise] didn't have a chance of making the team."