Disclaimer: this article is not intended to be an exhaustive treatise covering every aspect of punctuation. That wouldn’t make for a fun Medium post. If you are interested in wading through more comprehensive details than I provide here, you’ll find many good resources available online, such as here.
Okay, let’s start with the three punctuation marks that can be used to close sentences.
The period (.)
The period (or full stop in British English) is placed at the end of sentences and shorter statements intended to be viewed as complete thoughts.
Remember that sentences can be complex, lengthy, and made up of multiple sub-clauses, flowing on from one clause to another. They can also be short.
The other main use of the period is to indicate an abbreviation, which is a shortened form of a word. For example, etc. for etcetera, or in the following passage, where Kafka protects the identity of his protagonist by just giving us the first letter of his surname:
Some writers and publishers, particularly in American English, also include periods in acronyms (e.g. O.P.E.C.) and initialisms (e.g. F.B.I.), arguing that because each letter is essentially an abbreviation of a word, periods are necessary. However, such practice is fairly rare these days, with most writers and publishers omitting periods in acronyms and initialisms.
The question mark (?)
Why do we have this punctuation mark?
Answer: to indicate a question.
The exclamation point (!)
The exclamation point (or exclamation mark in British English) is used to express excitement, surprise, anger, or any other such strong emotion.
Note: Exclamation points tend to have most impact when used sparingly. You have been warned!
Next, three punctuation marks that are all used to show the separation of ideas or elements within a sentence.
The comma (,)
The comma is a very useful punctuation mark, helping to break up different parts of a sentence by introducing a brief pause.
The humble comma also has various other uses too:
- To separate items in a list (e.g. The milkshakes contained strawberries, raspberries, and bananas).
- To make large numbers easier to read. (e.g. Her house sold for £750,000).
- To show who is being spoken to in direct address (e.g. Hello, dear reader or Thank you, Sarah or Sir, it was a pleasure to meet you).
- To separate the spoken words from other parts of the sentence when writing direct speech (e.g. “I love you,” she said or She said, “I love you”).
The semicolon (;)
Many people find the semicolon the trickiest punctuation mark of all; indeed, many people avoid using it altogether. However, used correctly, it certainly has its place.
Semicolons link together two independent clauses that are closely related. A good way of thinking of them is that they represent a more significant break or pause between independent clauses than a comma provides, but slightly less of a break or pause than a period suggests.
Let’s look at a couple of examples of famous opening lines:
In both cases, Tolstoy and Camus could have used a period to divide their two clauses into two separate sentences. However, by using a semicolon both writers indicate that there is a close enough relationship between what comes before and after the punctuation mark for us to view the two parts as being part of the same sentence.
Note that in these examples what the writers could not have done is replace the semicolon with a comma (a common mistake known as a comma splice), as commas are too weak to be able to connect independent clauses (unless, of course, there is also a coordinating conjunction…).
The other use of semicolons that I’ll mention briefly is to separate items in a list or series when any of the items in the list contain commas (e.g. You may choose a chicken, ham, or cheese sandwich; a soft drink; and a slice of cake or piece of fruit).
The colon (:)
Colons are used between independent clauses, when the second clause explains the first.
Or, to give another example, here’s the memorable opening to The Go-Between:
There are also a few other common uses for the colon:
- To introduce a list (e.g. The soccer tournament had three age categories: under 11s, under 14s, and under 16s.). Do note, however, that, strictly speaking, a colon should only be used to introduce a list when what comes before the colon could stand as a complete sentence in its own right. So, in formal writing you should avoid introducing a list with phrases such as …the following: as this is not a complete sentence.
- To introduce a quotation (e.g. see how I introduced the L. P. Hartley quote above).
- Other uses of colons include when writing out times (12:30pm), ratios (1:3), and biblical references (Genesis 1:1–3).
Finally, we’ll now touch on some of the remaining punctuation marks.
The apostrophe (’)
The apostrophe is used in contractions to show that one or more letters have been omitted, as when we write can’t in place of can not. In the following example, from To Kill a Mockingbird, the word them has been shortened (or contracted) to ’em and it is has been shortened to it’s:
The other main use of the apostrophe is to show possession. Thus, the diary that belongs to Anne Frank is Anne Frank’s diary.
Do pay particular attention to where you place the apostrophe when dealing with plural nouns, as it can change the meaning of the sentence. For example, the boy’s dog refers to a dog belonging to one boy, whereas the boys’ dog indicates that the dog belongs to more than one boy.
While the use of the apostrophe to show possession is simple in most cases, it is possible to get one’s knickers in a twist, so to speak, when it comes to certain constructions. If you’re in any doubt, do consult a good reference (e.g. here or here).
Quotation marks (“ ”)
Quotation marks indicate to the reader that the text they contain is being reproduced word for word, exactly as it was spoken (or written).
When it comes to using quotation marks, the tricky part is often working out whether other punctuation marks should go inside or outside of the quotation marks. Interestingly, when it comes to commas and periods, the answer to this conundrum depends on where you live. In American English, commas and periods that are part of the overall sentence always go inside the quotation marks, even though they might not be part of the original quotation:
It was annoying, but then, as my grandmother used to say, “such is life.”
However, in British English and in most other variants of English, unquoted periods and commas are placed outside the quotation marks:
It was annoying, but then, as my grandmother used to say, “such is life”.
The ellipsis (…)
An ellipsis is a set of three periods indicating an omission.
I went undercover to the underpass to meet up with … an associate of mine.
Note that if you are quoting material in formal writing and wanting to use ellipses to show that some text has been omitted, it’s worth referring to your publisher’s or organization’s style guide, as there are some nuances to be aware of and different groups follow different conventions.
Another common use of ellipses is to show a brief pause in the flow of a conversation or thought:
Or to indicate in direct speech that the dialog trails off at the end:
“I meant to pay him back, but somehow…
Note that in such cases, the usual end-of-sentence period is left off.
The hyphen (-)
The hyphen is used to join together words that make up compound phrases. They notify the reader that two or more words or elements in a sentence are closely linked. Some examples of compound phrases that always take hyphens include day-to-day, open-minded, and so-called.
However, in truth, the correct use of hyphens in compound phrases (where more than one word is joined together and the phrase taken together is used to modify another word) can be tricky. A good rule of thumb to remember is to use a hyphen in a compound modifier when the modifier comes before the word it’s modifying:
It was a rock-hard cake, but I ate it anyway.
But note that (in most cases) the same compound phrase will not need a hyphen when it comes after the word it modifies:
I tried the cake but it was rock hard.
Hyphens are also used in all sorts of other scenarios:
- When writing compound numbers from twenty-one through ninety-nine (as shown in the Hemingway quote above).
- When stating the ages of people or things (e.g. We have a two-year-old child).
- When writing fractions as words (e.g. I ate two-thirds of the pizza).
There are various other uses, besides these. See here for more details.
The em dash ( — )
The em dash is a very versatile piece of punctuation. When used as a pair, em dashes can mark out non-essential clauses in the same way that commas or parentheses can. Here’s an example from Moby Dick:
Sometimes writers use an em dash in the place of a colon (e.g. He was given the verdict — guilty), but this is probably best avoided in formal writing.
So, there you have it. Basic punctuation in a nutshell. I realize that I’ve not covered the en dash –, parentheses ( ), brackets [ ], nor slashes /, but am going to stop here. After all, you can have too much of a good thing.
If you enjoyed reading this, you may also be interested to read some of my other pieces, for example:
I will close with one last literary quote — partly because it’s a brilliant opening to a memorable book (I, Claudius), and partly because the author (Robert Graves) successfully manages to use many of the punctuation marks we’ve discussed in one single sentence:
I, Tiberius Claudius Drusus Nero Germanicus This-that-and-the-other (for I shall not trouble you yet with all my titles) who was once, and not so long ago either, known to my friends and relatives and associates as “Claudius the Idiot,” or “That Claudius,” or “Claudius the Stammerer,” or “Clau-Clau-Claudius” or at best as “Poor Uncle Claudius,” am now about to write this strange history of my life; starting from my earliest childhood and continuing year by year until I reach the fateful point of change where, some eight years ago, at the age of fifty-one, I suddenly found myself caught in what I may call the “golden predicament” from which I have never since become disentangled.
— Robert Graves, I, Claudius