Use ‘s to show possession, even if it ends in s:
You only leave off the last s if you are adding ‘s to a word that is already a plural:
Reuters’, United States’
Do not use apostrophes when naming a decade or century:
If you are quoting what someone said, but need to add words to make the meaning clear, use brackets to add the words:
She said, “Let them [the poor] eat cake.”
If a full sentence is in brackets, put all punctuation inside the brackets.
What comes after a colon explains or gives examples of what comes before the colon:
I have three weaknesses: wine, women and song.
He did not go home: the road was washed out.
See the style guide under commas.
Use dashes to show an aside, to add something to what you are saying:
You know, I did not like him at all – he would never stop talking.
Use sparingly, even if Emily Dickinson loved them. In most cases a colon or comma will do just as well.
On the Internet a dash can be represented as a hyphen with a space before and after it:
It was horrible – I will never go back.
This is the BBC practice.
Others use two hyphens with no spaces around them:
It was horrible–I will never go back.
This is what The Economist does. Either is fine.
I have gone back and forth on this one, but I think the first is better since it always allows a space between each word.
full stops or periods: .
Use at the end of a sentence.
Do not use them at the end of abbreviations:
Dr Will was evil.
Put these around something added to a sentence that could be left out without changing its meaning:
I drove to Santa Fe (I was last there ten years ago) and then got some sleep.
You can put one or more sentences in parentheses if they are something the reader does not have to read.
If the parentheses includes a full sentence, then any punctuation it needs must also go inside. (Like this.)
question mark: ?
Put at the end of a sentence with a question, even if the question part is not at the end:
Where could he get a drink, he wondered?
quote marks: “
See the style guide under italics and quotes.
Use this to join two sentences that could stand on their own, but would seem overdone if you did:
I found my dog; he was asleep under the car.
This is better than:
I found my dog. He was asleep under the car.
This makes the event seem overly important.
Use semi-colons sparingly.