Use ellipses in quotations to indicate that you have omitted words or whole sentences. For omissions within a sentence, replace the omitted words with a three-point ellipsis mark (. . . ):

For omissions of whole sentences, keep the period (or other end punctuation mark) at the end of the sentence preceding the omission:

“We hold these truths to be self-evident, that all men are created equal. . . . The history of the present King of Great Britain is a history of repeated injuries and usurpations, all having in direct object the establishment of an absolute Tyranny over these States.”

See more detailed information about using ellipses.

In social e-mail, people often use ellipses to trail off or to show hesitation or shyness. Do not do that in more formal writing.