Two marks of punctuation, square brackets and the ellipsis mark (three spaced periods), show readers that you have modified a quoted passage in some way.
Brackets are used for additions, as in the following example from a paper on Khaled Hosseini’s novel A Thousand Splendid Suns.
Laila, fearful, confides in Tariq: “It’s the whistling, the damn whistling [of the rockets], I hate more than anything” (156).
Because some readers might not understand the meaning of whistling out of context, the writer has supplied a clarification in brackets. Brackets are also used to change words or letters to keep a quoted sentence grammatical in your context, as in the last example in L5-c, or to change a capital letter to lowercase or vice versa, as in L6-a.
The ellipsis mark is used to indicate omissions. In the following example from a paper on Tim O’Brien’s “How to Tell a True War Story,” the writer has omitted some words from the original in order to keep the quoted passage brief.
O’Brien warns his readers bluntly that they should not seek noble themes in war stories: “If at the end of a war story you feel uplifted, . . . then you have been made the victim of a very old and terrible lie” (347).
If you want to omit one or more full sentences from a quotation, use a period before the three ellipsis dots.
O’Brien regards war as fundamentally immoral: “A true war story is never moral. . . . If a story seems moral, do not believe it” (347).
Usually you do not need an ellipsis mark at the beginning or at the end of a quotation. But if you have dropped words at the end of the final quoted sentence, put three ellipsis dots before the closing quotation mark and parenthetical reference, as in the example in L6-a.
Remember to use brackets and ellipsis marks sparingly. The purpose of quoting is to show your readers the actual language of the work. Excessive alterations can undermine a quotation’s effectiveness as evidence.