An ellipsis (plural: ellipses) is a punctuation mark consisting of three dots.
Use an ellipsis when omitting a word, phrase, line, paragraph, or more from a quoted passage. Ellipses save space or remove material that is less relevant. They are useful in getting right to the point without delay or distraction:
Full quotation: "Today, after hours of careful thought, we vetoed the bill."
With ellipsis: "Today … we vetoed the bill."
Although ellipses are used in many ways, the three-dot method is the simplest. Newspapers, magazines, and books of fiction and nonfiction use various approaches that they find suitable.
Some writers and editors feel that no spaces are necessary.
Example: I don't know…I'm not sure.
Others enclose the ellipsis with a space on each side.
Example: I don't know … I'm not sure.
Still others put a space either directly before or directly after the ellipsis.
I don't know …I'm not sure.
I don't know… I'm not sure.
A four-dot method and an even more rigorous method used in legal works require fuller explanations that can be found in other reference books.
Rule 1. Many writers use an ellipsis whether the omission occurs at the beginning of a sentence, in the middle of a sentence, or between sentences.
A common way to delete the beginning of a sentence is to follow the opening quotation mark with an ellipsis, plus a bracketed capital letter:
Example: "… [A]fter hours of careful thought, we vetoed the bill."
Other writers omit the ellipsis in such cases, feeling the bracketed capital letter gets the point across.
For more on brackets, see Parentheses and Brackets.
Rule 2. Ellipses can express hesitation, changes of mood, suspense, or thoughts trailing off. Writers also use ellipses to indicate a pause or wavering in an otherwise straightforward sentence.
I don't know … I'm not sure.
Pride is one thing, but what happens if she …?
He said, "I … really don't … understand this."