What is an ellipsis? Ellipses (plural) are formed by three periods in a row, and they are mainly used to indicate that some verbiage has been omitted from a quotation.
“O, Romeo, Romeo, wherefore art thou . . . and I’ll no longer be a Capulet.”
Traditionally, the ellipsis is formed with a period-space-period-space-period, with a full space on either side of it. However, in the digital world, you can run into problems with this form because the three periods might become split up during line wrapping. Therefore, I would advise using the Autocorrect option in Word to substitute an ellipsis symbol (…), which is Unicode 2026, for the dot-space-dot-space-dot. This will help keep all your ducks, I mean dots, in a row.
Sometimes your omitted verbiage falls at the beginning or end of a sentence, near a comma, or between two sentences, rather than in the middle of a sentence.
If the omission is at the end of the sentence, use an ellipsis and period (four dots, no spaces):
“Deny thy father and refuse thy name; or if thou wilt not….”
If the omission is before a comma in midsentence, use an ellipsis and comma (no space before the ellipsis):
“Deny thy father…, and I’ll no longer be a Capulet.”
If the omission is after a comma, keep a space on either side of the ellipsis:
“O Romeo, … art thou Romeo?”
If the omitted verbiage is at the end of a question, use an ellipsis and ? (no spaces):
“O Romeo, Romeo, wherefore…?”
If the omission is one or more sentences between two full sentences, use a period at the end of the first sentence, then a space followed by the ellipsis, then another space before the second sentence.
An ellipsis is sometimes used to indicate a pause in a quoted speech. It can also be used instead of an em-dash to indicate an unfinished thought in dialogue, or a trailing off in mid-sentence into silence.
Here’s an example I find myself saying more often the older I get:
“I came into this room to….”
One more rule: Never use an ellipsis to indicate “etc.”