MLA 9 Resource Center: Square Brackets and Ellipses

[ ] Used when a writer needs to include additional information to a quotation. 

• adds explanatory information 
  • Joey said "She [Pam] went to the store."
• change quote to fit a sentence 
  • "If you rest, you rust." - Helen Hayes 
  • According to Helen Hayes, "If [I] rest, [I] rust," so I must continuously work to achieve my goal of becoming an actress.
• adds emphasis to certain words [italics added], [bold added]
• Helen Hayes says, "If you rest, you rust," [bold added].

Ellipsis (plural:ellipses): a punctuation mark consisting of three dots (. . .) 

Used: when omitting a word, phrase, line, paragraph, or more from a quoted passage. 

Examples

• Alexander Graham Bell once said "When one door closes ... we often look so long and so regretfully upon the closed door that we do not see the one which has opened for us."
• "Huckleberry came and went, at his own free will. He slept on doorsteps in fine weather and in empty hogsheads in wet; he did not have to go to school or to church ... he could go fishing or swimming when and where he chose...In a word, everything that goes to make life precious that boy had" (76).