The . (period) is used to end a sentence. If you string thre of these together like so, "..." you get what resembles a pause.
This is the sentence, and here's the end.
Bob: "Why did you do that?"
Bob's son: "Um... uh... I... I don't know
Bob: "Why did you do that?"
Bob's son: "Um... uh... I... I don't know
by Mike October 15, 2004
by Oxidol January 21, 2019