There are three different ways to end a sentence. There is a correct use for each, despite the fact that they are frequently confused.

Full stops

The full stop is used at the end of a sentence that is not a question or an exclamation.

Question marks

The question mark is used at the end of a question. This may seem obvious, but it can be misused. Make sure that the sentence is a question, and always do use a question mark when asking a question – even if it’s a heading or a title.

Examples

Can you help me fill out this form? – This is a question, so uses a question mark.

I wonder if you could help me fill out this form.  This is not a question, so uses a full stop.

If only part of the sentence is a question, it needs to be split into two sentences

Example

Could you help me with this, because I don’t understand it.

This is a bad sentence – split it into two sentences instead:

Could you help me with this? I don’t understand it.

Exclamation marks

Exclamation marks are used for an exclamation.

Examples

Help!
Merry Christmas!
Down with this sort of thing!

Exclamation marks to show excitement

Never use an exclamation mark to denote excitement in a formal setting. The writing should convey this.

Using multiple exclamation marks

You would never use more than one full stop, or more than one question mark. Never use more than one exclamation mark.

Spaces and sentence-ending punctuation

Generally, one space – and no more – should follow a full stop, exclamation mark or question mark. Style guides may differ in this regard. Editors fight mercilessly over it. Whatever you do, be consistent.