Ellipses …

An ellipsis is a sequence of three dots (using full stops) that has 2 functions:

to show where text has been intentionally left out, particularly in a quote
to show an interrupted or incomplete thought.

In the second case, ellipses are also called suspension points.

Quotes

Show you have left text out

The auditor cited ‘2 examples where ... we need to correct the accounts’.

The most common use of the ellipsis is to condense a quote by showing where you have left text out of an otherwise verbatim quote. This will either be to save space or to focus on the most relevant content.

The CEO stated, ‘Our focus for the year ahead must be on sales growth.’

The CEO stated, ‘Our focus ... must be on sales growth.’

If you're leaving an entire paragraph out of a quote, put the ellipsis on a separate line to flag this to your readers.

Suspension points

Show an implied or incomplete thought

Perhaps one day ...

You can use the ellipsis if you want a sentence to trail off with a deliberately incomplete thought. This suggests you are leaving the reader to speculate or complete the sentence based on context.

Save this kind of construction for less formal text, such as emails, or in more literary work, such as poetry. Avoid it in formal workplace writing, because it can come across as sloppy or even sarcastic.

I thought we were meeting at 1 pm ...

I thought we were meeting at 1 pm, but did I have the wrong time?

When an ellipsis ends your sentence, you don’t need to add a full stop after it.

Formatting

Put a space on both sides

The auditors insisted on 3 changes ... before they would sign the accounts.

A common challenge with using ellipses is how to create them. Although they use the same character as a full stop, ellipses space them out differently to 3 ordinary full stops side by side.

Fortunately, MS Word can automatically generate an ellipsis if you type three full stops. If this setting is switched off, you can insert an ellipsis through the Insert > Symbol menu.

Put a non-breaking space before the ellipsis, and a regular space after it.