Punctuation (e.g., commas, hyphens, semicolons, dashes) improves clarity by showing how words are grouped, separated, or linked. This lesson explains the uses of the main punctuation marks with example sentences.
Table of Contents
The Main Punctuation Marks
Punctuation Use and Examples
Parentheses (Round Brackets)
Period (Full Stop)
The Main Punctuation Marks
Here are the main punctuation marks in English grammar. Each of these links will take you to a comprehensive lesson (with a test) on how to use the punctuation mark.
Here are succinct explanations covering the different ways that each of the main punctuation marks is used. This is an important page on Grammar Monster. Punctuation controls how information is grouped, how it flows, and how it is emphasized. In other words, it controls how your readers absorb your words. Using punctuation correctly is essential to add clarity and precision to writing.
Apostrophes are used:
(1) to show possession
The ball is next to the dog's kennel.
(Look at the position of the apostrophe. This is correct for the kennel of one dog.)
The ball is next to the dogs' kennel.
(This is correct for the kennel of more than one dog.)
Show me the children's den.
Is that Mr. Jones' car?
These are called possessive apostrophes because they show possession. The positioning of possessive apostrophes causes some writers a headache, but here is a simple rule that works every single time:
Everything to the left of the apostrophe is the possessor, spelled perfectly.
Time fly's like an arrow. Fruit fly's like a banana.
(This should be "flies.")
Using an apostrophe to show a plural is considered a bad mistake – it is the pet peeve of lots of people. If you make this mistake too often, your readers might start to question your education and even your wider abilities! Be warned.
Read more about apostrophes used with plurals.
(2) randomly before the letter "s"
Lee like's cakes.
(This should be "likes.")
Your article reads like it was written by Charles Dicken's.
(This should be "Dickens.")
Summary of Apostrophes. Apostrophes are primarily used for possession and contraction in English. Using apostrophes correctly shows attention to detail and your command of English. We have lots of lessons on the different aspects of apostrophe usage, but if you want it all in one place, here is a lesson that summarizes everything about using apostrophes.
Colons are used:
(1) to expand on something previously mentioned
I need just one personal trait: loyalty.
There are only three things that matter: love, chocolate, and ice-cream.
The colon is like an equals sign (=).
In the first example, "trait" equals "loyalty." In the second example, the phrase "three things" equals "love, chocolate, and ice-cream." Note that the words after the colon are an expansion of something mentioned before the colon. Structuring a sentence like this is useful for emphasis, shock, or a punchline.
Read more about using colons to expand on things previously mentioned.
(2) after an introduction
I've seen the following: rust, slime, and a rat.
Please check the following:
(1) the fire extinguishers
(2) the smoke alarms
(3) the exit routes
A colon is used after an introduction for a list. The list could be written in a normal sentence or presented as bullet points. When the list is in a normal sentence (like in the first example above), the introduction before the colon must be an independent clause, which is nearly always created by using the words "the following." With bullet points, there is more leniency on the structure of the introduction.
Read more about using a colon after an introduction.
He said: "Laugh at yourself first, before anyone else can."
John gave the following advice: "Do not eat any mushrooms from this field."
A colon can be used before a quotation. A comma is also an option. To warrant a colon, the introduction before the colon should be an independent clause or the quotation should be at least one complete sentence.
Read more about using colons with quotations.Summary of Colons. Colons are used to introduce lists, quotations, and expansions of things previously mentioned. The text after a colon always expands on something in the introduction before the colon. It is never an entirely new idea. Here is a lesson that covers all the points on using colons.
Before we look at the other types of punctuation, here is a widget that shows 50 writing mistakes involving punctuation:
Punctuation Errors (/50)
How serious is this error?
A comma is used:
(1) after setting the scene at the start of a sentence
In the middle of London, the traffic is scary.
When the mix has cooled a little, add the chocolate buttons.
(2) after words like However, Consequently, or As a result
I thought you were wrong. However, I now agree with you.
Jack has left the company. Consequently, the database is currently off line.
These terms are sometimes called "transitional phrases" because they help with the transition from one sentence to the next. However, grammarians call them conjunctive adverbs. It is a good practice to use a comma after a conjunctive adverb. Do not use a comma before though! That would be a mistake called a run-on sentence.
I thought you were wrong, however, I now agree with you.
(4) before a conjunction joining two independent clauses
Jill loves pies, and she likes cakes.
Jack went to university, but Jill emigrated to New Zealand.
Conjunctions are joiners. "And," "but," and "or" are common examples. If you look at the highlighted texts in the examples above, you will notice that they could be standalone sentences. Clauses that could be sentences are known as independent clauses.
When a conjunction is used to merge two "sentences" into one, there is a comma before the conjunction. (A sentence with more than one independent clause is called a compound sentence.)
Ensure each half of the sentence is an independent clause before putting a comma before your conjunction.
Jill loves pies, and likes cakes.
(This is wrong because "likes cakes" is not an independent clause, i.e., it could not be a sentence.)
The computer in my office, which belongs to my work, is covered in white paint.
The highlighted texts in the examples above are just additional information. They could quite easily be enclosed with round brackets or even deleted. If you think brackets look too stark or too informal, you can use commas as parenthetical punctuation. However, if the information is needed for identification, then do not commas. For example:
My sister, who lives next door, won the lottery.
My sister who lives next door won the lottery.
These are both correct. In the first example, "who lives next door" is just additional information. (It is called a non-restrictive clause.) A reader would infer that the speaker has only one sister. In the second example, "who lives next door" is required to identify the sister, so there are no commas. (It is called a restrictive clause.) A reader would infer that the speaker has more than one sister.
Read more about using commas as parentheses.
(6) to separate list items
Please buy some bread, honey, and jam.
Jack will visit Argentina, Brazil, and Chile.
Commas can be used to separate list items (e.g., cat, dog, rabbit). In a sentence, it is normal to use a conjunction (usually "and") before the last list item (e.g., I have a cat, a dog, and a rabbit.)
If there are just two list items, there is usually no need to use a comma before the conjunction (e.g., I have a cat and a dog.) However, if there are more than two list items, then a comma can be used before the conjunction. The comma before such a conjunction is called a serial comma or an Oxford Comma.
Americans tend to use the serial comma, but the British don't.
If it helps your reader, it is possible to show the end of a long or unclear subject with a comma. Be warned that this is not a popular practice among some grammarians, who believe that a subject should not be separated from its verb. However, you are in charge of your writing, and if you think the comma helps, you can use one.
Read more about using a comma after a long or unclear subject.
(8) after a long or unclear subject
Commas can be used with large numbers to make them easier to read. A comma is placed every three digit positions to the left of the decimal point. (They are not used to the right of the decimal point.)
Read more about using commas in numbers.
Granddad looked at me over the top of his glasses and said, "I've seen it all and done it all. I just don't remember any of it."
(A colon is an option here too.)
It is possible to use a comma to separate a verb of attribution (e.g., "say," "suggest," "tell") from a quotation. If the quotation is at least one complete sentence or the introduction is an independent clause, then a colon (:) is an option too.
Read more about using commas and colons before quotations.Summary of Commas. Commas have lots of uses, but generally they are used for separating and grouping. There is no need to fly by the seat of your pants with commas. The rules are not overly complicated. Mastery – real grammatical mastery – of commas is an essential skill for the serious writer. Here is a more comprehensive lesson with lots of examples on using commas, and here is an advanced but fun test on commas to help confirm your understanding.
Do not use too much cooking-oil with the potatoes.
Are you the man who looks after the paper-clips?
A compound noun is a noun made from at least two words. Sometimes, the words in a compound noun are hyphenated to show they are one grammatical entity. However, this is not always the case. Some compound nouns have morphed into one word (e.g., "greenhouse"), and some are written with spaces (e.g., "ice cream").
Read more about joining the words in a compound noun.
(3) with prefixes
Her holiday was ultra-expensive!
I would like to re-establish the weekly finance meeting.
Not every prefix should be hyphenated. Far from it! Generally, you should avoid using a hyphen with a prefix unless the unhyphenated word is a spelling mistake or it looks too unwieldy.
Read more about hyphenating prefixes.Summary of Hyphens. When used with a compound word, the main purpose of a hyphen is to show that the words are a single entity (e.g., a single adjective or a single noun). Hyphens are also useful to avoid ambiguity (e.g., a hyphen makes it clear that a paper-clip is a clip for paper and not a clip made of paper). When used with a prefix, the hyphen is for readability. Here is a more comprehensive lesson on using hyphens.
Parentheses (Round Brackets)
Parentheses () / Round brackets () are used:
(1) to insert extra information
Set in the 17th century, The Three Musketeers ("Les Trois Mousquetaires" in French) is a novel by Alexandre Dumas.
We are heading for a disaster (a total collapse of the banking system).
Great white sharks hunt by detecting electrical fields (They can detect less than one billionth of a volt) emitted by the movements of their prey.
The extra information in the parentheses is often an afterthought, a clarification, or an expansion of a recently mentioned idea. Note that there is no period/full stop after "volt" in the last example. (This is explained in the lesson on round brackets.)
(2) to present a plural option with a singular one
Your guest(s) must leave before midnight.
When the glue is dry, place the bolt(s) in its holder ensuring the head is still visible.
When showing a plural option alongside a singular one, do it only once (like the example above). The example below has been marked wrong because it is far too unwieldy.
When the glue is dry, place the bolt(s) in its(their)holder(s) ensuring the head(s)is(are) still visible.
"If you don't like them [my principles], well, I have others."
"If you don't like [my principles], well, I have others."
In the first example, the text in the square brackets follows "them" to explain what is meant by "them". In the second example, the text in the square brackets replaces "them." Both of these are acceptable ways of clarifying a quotation. The square brackets tell the reader that the bracketed text was not in the original quotation.
(2) to show that [sic] and [...] are insertions by the current author
The captain wrote: "The moral [sic] of the troops is dire."
"I fear not the man who has practised 10,000 kicks once but [...] the man who has practised one kick 10,000 times." (martial artist and actor Bruce Lee)
The abbreviation sic stands for sic erat scriptum (thus it was written). It is typically used to show that an error was in the original quotation. The three dots of an ellipsis are used to show that text has been omitted from the original quotation. The square brackets make it clear that the sic and the ellipsis were not in the original.
Read more about using square brackets.
Period (Full Stop)
A period () / full stop () is used:
(1) at the end of a declarative sentence
I eat pies.
Venus is the hottest planet in our solar system.
Great white sharks usually inhabit coastal waters where the water temperature ranges 12-24 degrees Celsius.
Periods can be used in initialisms (e.g., B.B.C., C.N.N., U.N.) and contractions (e.g., Prof., Rev. Capt.). Nowadays, however, periods in initialisms are rare, and you should avoid using them. (In other words, "BBC" and "CNN" are far more common than "B.B.C." and "C.N.N.") However, if the abbreviation is an organization and it uses periods in its own abbreviation, then you should too.
With contractions (e.g., Mr., Prof.), there are two conventions. In the US, there is always a period after a contraction. In the UK, however, there is only a period after a contraction if the last letter of the contraction is different to the last letter of the original word. For example:
Mr. Jones wants to invite Prof. Smith. ()
Mr Jones wants to invite Prof. Smith. ()
Read more about periods in contractions.Summary of Periods. Periods end certain types of sentence. That is their main use. This might seem simple, but periods are responsible for lots of writing mistakes, particularly the run-on sentence. When you have written a sentence, you must end it with a suitable end mark (e.g., a period, a question mark, an exclamation mark). You cannot put a comma and then write another sentence. This is a common mistake among otherwise competent writers.
(3) before a conjunction which merges two sentences containing commas
Yesterday, it was, to our surprise, sunny; but today, as expected, it's dull.
As covered in the commas section (point 4), you should use a comma before a conjunction (e.g., "and," "or," "but") that merges two independent clauses into one. If those clauses contain a lot commas, it is possible to use a semicolon before the conjunction to outrank those commas. This is an outdated practice nowadays, but if you think a semicolon helps to make the sentence structure clearer, you can use one.
Read more about using a semicolon before a conjunction.Summary of Semicolons. A semicolon is like a soft period (full stop) but a hard comma. The rules for using semicolons are clear, and they are detailed above. There are no other uses. Most proofreaders will tell you that semicolons rarely survive their cut because many writers use them incorrectly. Remember there is always an alternative to a semicolon.
President Reagan said: "You can tell a lot about a fellow's character by his way of eating jellybeans."
The words within quotation marks should be the exact words spoken or written. Any edits to the exact words must be shown with square brackets. For example:
President Reagan said: "You can tell [...] a fellow's character by his way of eating jellybeans."
Do not use quotation marks for reported speech. For example:
John's mother said: "John is a good boy."
John's mother said that "John was a good boy."
(These are not the exact words spoken.)
John's mother said that John was a good boy.
(This is an example of reported speech.)
The most common questions on quotation marks are about positioning punctuation. As a general rule, periods and commas at the end of a quotation go inside the quotation marks, while semicolons and colons go outside. Question marks follow logic. For example:
She said "Do you love me?"
(The quotation is a question.)
Did she say "I love you"?
(The quotation is not a question, but the sentence is.)
Did she say "Do you love me?"?
(The quotation and the sentence are both questions, which warrants two question marks. However, two is too unwieldy, so the outer one is omitted.)
I was certain the "Spruce Goose" was too heavy to fly.
Howard Hughes said: "I was certain the 'Spruce Goose' was too heavy to fly."
(When quotation marks are nested within quotation marks, switch to singles for the nested quotation. Be aware that some publishers do this the other way around (i.e., they start with singles and nest doubles). Follow your local convention to choose your starting quotation marks, which are likely to be doubles.)