Smart quotes should not be confused with straight quotes (“), which is the computer’s default form.In addition, single straight quotes are often used as prime marks; as the symbol in measurements, such as feet and arcminutes; and in mathematics, as in x’y’; however, this is not the correct usage—the prime symbol (ʹ) should be used instead.
Many of the rules that follow are based on the premise that quotes should be carefully selected to stand on their hind legs and sing.
And because they deserve special attention, they deserve careful handling by reporters and editors.
For example, if you are inserting a direct quote into your writing, it is important to ensure that the reader understands that those words are not yours.
In a story that includes conversations among the characters, quotation marks distinguish their words from those of the author.
If a quote is not understandable without parenthetical explanation, it probably should be a paraphrase rather than a direct quote. If, in the context of the story, the antecedent of the pronoun is clear, leave it.
If a speaker has used a pronoun for a proper name, don't automatically remove the pronoun and insert the proper name in parentheses on the assumption that the reader is stupid. The insertion of parentheses in quotes should be the exception rather than the rule.
The correct use of quotation marks can be confusing for authors, especially those whose primary language is not English (ESL authors).
Quotation marks are used to show that the text is taken word for word from another source, to call attention to an important word or phrase, or when using a technical term for the first time.
Quotation marks are also used to call attention to new words or phrases, which is particularly useful in science and technical writing, such as in the following sentence: One of the several branches of zoology, “ichthyology,” concentrates on the study of fish.
Note that, in keeping with the American English style, not only is the new term in double quotes, but the comma is inside the quotation marks.