According to the Chicago Manual of Style, use the term "ellipsis" for omissions but the term "suspension point" for delays and interruptions. In both cases, three dots appear. Luke Taylor, host of Minnesota’s Public Radio’s Grammar Grater, states that ellipsis marks as a pause appear frequently in less formal writing, such as dialogue.
All sources agree that ellipses should appear on the same line of print. Always insert a space both before and after ellipsis marks, according to according to Luke Taylor. The Chicago Manual of Style prefers three spaced dots; similarly, Modern Language Association style calls for spaced dots but no longer requires brackets around ellipses except for clarity, according to Purdue’s OWL. Some style manuals prefer reduced spaces (or no spaces) between ellipses […]. Formatting may occur automatically in word processing programs when you enter three consecutive dots.
If you intentionally use a grammatically incomplete quotation at the end of a line, only three dots appear, according to the Chicago Manual of Style. Consider this example: The sleepy child said, "I whacked the mean witch with a . . ." If the thought were complete, however, a period would appear after the last word, with a full space before the ellipsis, resulting in four dots.
Exclamation and question marks occur (without a space) at the end of each of the three sentences that follow. In this example, the pauses represent the other speaker’s omitted (but implied) words: "Hello, I’ve been on hold for 20 minutes! . . . Why should I continue to hold? . . . Yes, I know that you are busy! . . ." After the end punctuation mark, add a space and then the ellipses. Treat all end marks the same, according to Taylor.
If a pause occurs within a sentence, add space both before and after the ellipsis marks. Consider this squeamish hesitation: "I just can’t eat . . . fried insects," Alice said.
Informally, the ellipsis mark has become popular to indicate a pause or break in email, according to Taylor. An email sender might use ellipses to express fragmented thoughts. Note, however, that style and grammar manuals discourage overuse of ellipses as a substitute for other punctuation and warn writers that misuse can alter meaning.