Punctuation Rules

Language is a glorious game, my friends, for players of all ages, and for any game to work, it needs rules. They may be joyless, they may cause arguments, but where would we be without them? Knocking at the door of the Tower of Babel, that’s where.

So, here are a few pointers on how to employ some of our favourite punctuation marks correctly.

Full stop, period or decimal point

The most familiar of all our punctuation buddies and possibly the easiest to use, the full stop marks the end of a sentence. Some sentences can be very short (Sorry.), but still the full stop brings them to an efficient close.

They can also show abbreviations (approx., etc.). In American English, the periods have been kept at the end of Dr. and Mrs. or in between the initials of F.B.I. or Ph.D., but generally they have fallen out of use in British English (Prof or MFI, for example). This is still a slightly fluid situation, though, so a style guide will often have the final say.


There are a disorienting number of rules and grammatical points about the comma, but put briefly, they are used to separate and organise thoughts within a sentence.

They can be used to separate words, clauses, or phrases when they appear in lists. They can be used to slip some extra, non-essential information into a sentence or add a participial phrase. They can tag questions, can’t they? Yes, they can also add interjections to a sentence.

Exclamation marks and question marks

Exclamation marks can be used to express exasperation or surprise (Help! Wow!) or even sarcasm (Cool story, bro!). They can also be used when a command is being issued (Get down!).

Question marks are usually, but not always, found at the end of an interrogative sentence, even if it is quite a long one. However, they do not appear if the question is a reported one (e.g., He asked me why I wasn’t playing tennis these days.)

Both marks can be found piled up at the end and in the middle of texts or social media comments (As if!!!! You’re married??!!), often mingled with a host of emoticons. This isn’t normally welcomed in formal writing.

Quotation marks and inverted commas

The Atlantic wall separates mirror-image versions here with American English choosing to surround quotes with double marks (“”), while Brits use the single inverted commas (‘’). Americans will then use inverted commas for quotes within quotes, while Brits will do the opposite – double marks within single marks.

More frustratingly, American English generally places the other punctuation like commas or periods inside the quote (My favourite film is “The Big Lebowski.”), whereas in Britain only punctuation within the actual quote is included (I prefer ‘Passage to India’.).

Hyphens and dashes

Hyphens are generally shorter than dashes and restricted to appearances in compound words (heart-breakingly under-appreciated), whereas dashes are used in place of a variety of other punctuation marks – commas, parentheses, and colons.

Parentheses and brackets

There has been some lexical drift here, as parentheses – the rounded symbols ( ) – are often called brackets – more properly, the symbols with squared edges [ ]. The latter are only used in an editing context to highlight mistakes or changes in the original text or to add some clarification. Many authors will try to keep pairs of parentheses apart, though there are no grammatical rules on this.


A controversial little punctuation mark, but its twin roles are quite easy to define. Either the apostrophe indicates contraction (where a letter or letters have been removed, like didn’t or ha’penny) or possession (Dave’s bike, the cat’s pyjamas). It shouldn’t be used for multiples, unless describing a decade in American English (McCarthyism in the 1950’s).

The third person singular possessive (its), however, should take some blame for the confusion around apostrophes, as its appearance seems to fall somewhere in between his and her and a possessive noun.

Colons and semi-colons

Finally, tasty punctuation for the real connoisseur or connoisseuse. In terms of rules, colons should always be preceded by a full sentence and followed by a capital letter (in American English) or a lower-case letter (in British English). Semi-colons should be used to link together independent clauses, sometimes taking the places of conjunctions like and or but, or in place of commas in a list, if the items on the list themselves contain commas.