How to punctuate a sentence
Last month I showed how to unstuff a sentence by removing unnecessary words. This month I’ll offer a quick-and-dirty guide to punctuating a sentence. Nothing that follows is meant to substitute for the nuanced explanations of what’s usually called a writing handbook, the sort of book that college students purchase in a first-semester writing course. These five rules though have the virtue of being manageable, which is difficult to say of a 1,000-page book. In each paragraph that follows, the sentences illustrate the punctuation rule involved. Note that I’m avoiding almost all grammatical terminology. Instead, I’m emphasizing a small number of sentence patterns.
Rule one
If your sentence begins with an introductory element, put a comma after it. Even if it’s a short element, put a comma after it. In time, you’ll be putting this comma in without having to think about it.
Rule two
Any element which interrupts the movement of the sentence, whether it’s big or small, should be set off with commas. This sentence, like the first, also has an element set off with commas. An element that appears at the end of the sentence should also be set off with a comma, as I’m showing here.
Rule three
Items in a series should be separated with commas. What do I mean by “items in a series”? Wine, women, and song. Life, love, and laughter. Crosby, Stills, Nash, and Young.
Rule four
Complete sentences that are joined by a coordinating conjunction (and, but, for, nor, or, so, yet) need a comma before the coordinating conjunction. That might seem obvious, but this comma frequently gets left out. Putting it in makes a sentence more readable, and any reader appreciates that.
Rule five
Complete sentences that are joined without a coordinating conjunction need a semi-colon instead of a comma; the semi-colon shows the end of one sentence and the beginning of the next. Semi-colons are often followed by a connecting word or phrase; however, a connecting word or phrase is not necessary. Sentences joined with only a comma are called comma splices; they’re among the most common errors that come up in college writing.
(Note: In the next-to-last sentence in the previous paragraph, there’s a comma after however because it’s an introductory element in the second sentence.)
Fixing comma splices requires familiarity with two recurring sentence patterns. The first involves a complete sentence, a semi-colon, and another complete sentence:
[complete sentence]; [complete sentence].
Some examples:
Your argument is persuasive; it addresses every objection I had.
His research paper is plagiarized; he is going to fail the class.
The novel is a relatively recent literary form; it’s not nearly as old as epic poetry and lyric poetry.
The second pattern to look for involves a complete sentence, a semi-colon, a connecting word or phrase, a comma, and another complete sentence:
[complete sentence]; [word or phrase], [complete sentence].
(Again, the comma after the connecting word or phrase is appropriate as that word or phrase is an introductory element in the second sentence.)
Some examples:
I decided not to take the job; instead, I’m going to graduate school.
The proposal is flawed; as a result, we’re sending it back for revision.
She did well in the class; in fact, she did much better than she had expected.
How can you tell whether you have two complete sentences or one sentence with an interrupting element at its end? With an interrupting element (something less than a sentence in itself), the parts of the sentence can be switched and still make sense:
I’ll go to work, even though I’m sick.
Even though I’m sick, I’ll go to work.
But with a second complete sentence and a word or phrase such as instead, as a result, or in fact, the parts cannot be switched and still make sense.
Those are the basics of punctuating sentences with commas and semi-colons. I know from working with many students that any writer can get better when it comes to punctuation. The key is the ability to recognize a handful of familiar patterns. Look for the patterns in your sentences, and you too can get better. With some practice, you’ll be able to see the parts of your sentences falling into place, and punctuating correctly will become, believe it or not, a habit, one that you’ll be happy to have acquired.
Colons, by the way, function as arrows or pointers: see what I mean?
Michael Leddy teaches college English and blogs at Orange Crate Art.




Comments
Caleb says on April 5th, 2007 at 11:54 am
As a copy editor of a newspaper, I feel I should add something for all you English nuts. AP style demands much more brevity. Therefore, some alterations to punctuation rules apply. These alterations nullify all of the rules above, which are otherwise very good rules.
Please do not whine about how bad your local newspaper’s grammar is for not following these types of rules. Usually, it is an issue of style, though I have seen truly atrocious newspaper grammar.
seb says on April 5th, 2007 at 1:12 pm
What about dashs? How to use them, or don’t use them?
M@ says on April 5th, 2007 at 9:10 pm
I see in your rule three you’re implicitly endorsing the Oxford comma. Heathen.
; )
Michael Leddy says on April 5th, 2007 at 10:39 pm
@seb: I tried leaving a comment earlier, but for some reason it didn’t take. I like dashes and make much use of them in my writing. I’d suggest thinking of the dash (or a pair of dashes) as way to set off a strongly interrupting element, one that a comma (or a pair of commas) can’t handle. Here’s an example, a sentence from a recent article by Nicholas Wade in the New York Times : “These four kinds of behavior — empathy, the ability to learn and follow social rules, reciprocity and peacemaking — are the basis of sociality.”
(I’ve added a space on each side of the dash to prevent strange text-wrapping.)
@M@: Yes, I like that comma. If it goes in, there’s never the ambiguity that can sometimes arise when it’s absent. And since some readers will see this comma’s absence as an “error,” I think it’s good to keep it in.
Thanks for the comments!
Michael Leddy says on April 5th, 2007 at 10:45 pm
What is it about leaving a comment that inspires typos? I should have said “as a way to set off a strongly interrupting element.”
RD says on April 6th, 2007 at 8:42 am
Thanks, Michael, I find these tips to be very helpful. For those people at my office who tend to write their emails in run-on sentences, I would like to engineer a way for them to “accidentally find” this page. ;-)
I saw one possible item that you could have touched on in your lesson, in the area of semicolon usage: I would like to have seen a few tips on when it is stylistically preferable to actually use two separate sentences, rather than join two sentences with a semicolon.
Novice says on April 6th, 2007 at 9:03 am
Amazing!
I read detailed explanations on the usage of commas and semi-colons in different books and on many sites, but the end result was the same: I could never really figure out the difference between the two, and now your simple explanation drives the point home ;) Thank you!
Michael Leddy says on April 6th, 2007 at 10:38 am
I left a longish comment last night about dashes and the “Oxford comma,” but it seems to have vanished. The comment that I left above corrected a typo in that comment.
I’ll add something soon about these matters and about when separate sentences might be a better choice than a semi-colon.
Type Nut says on April 6th, 2007 at 3:26 pm
Thanks, Michael, I’m sure many people will find your tips and examples helpful.
For those who do look to using dashes, please remember the difference between the hyphen (-) and a dash. The dash is a different punctuation mark, typically set as an em-dash — a dash as wide as the letter ‘m’ in the current font — or as double-dashes when an em-dash can not be typed (as is the case here). When an em-dash can be used, the surrounding space should be omitted.
knubie says on April 6th, 2007 at 3:44 pm
Rule 4 is incorrect. The word ‘and’ does not need a comma before it. I checked with a college professor and with our magazine editor,
Horst Grundkenfelder says on April 6th, 2007 at 3:46 pm
Regarding rule three: when commas occur within the individual items of a list, semicolons (rather than commas)should be used to separate the items from one another.
Stephen says on April 6th, 2007 at 3:54 pm
Thanks for publishing these helpful tips. One question: Is it correct to place commas and other punctuation within quoted elements, or outside them? For example:
… just a “kid thing,” but I …
… just a “kid thing”, but I …
brusp says on April 6th, 2007 at 3:54 pm
very good tips. there are so many people i would love to hit in the face with a physical manifestation of this blog..
tech says on April 6th, 2007 at 4:06 pm
What about dashs? How to use them, or don’t use them?
Paul says on April 6th, 2007 at 5:41 pm
I love proper grammar, the English language, and the Oxford comma.
Axalover says on April 6th, 2007 at 5:44 pm
“Any element which interrupts the movement of the sentence, whether it’s big or small, should be set off with commas.”
The word “which” is incorrectly used in the quoted sentence. The word “that” is correct. Were “which” correct, it would be preceded by your friend “,”…
Sam says on April 6th, 2007 at 9:37 pm
T H A N K Y O U
Raza says on April 6th, 2007 at 10:39 pm
My grammar handbook says conjunctions like ‘and’ need a comma before them only when the clauses preceding and following it are independent. Otherwise, no comma is required.
David says on April 6th, 2007 at 10:48 pm
You have made a really good brief on punctuation, but I do find one through four to be quite obvious. I had to read five a few times to understand it, it could be surmised as: ‘If the sentence is able to be split into two, but the second too short and dependent on the first to be awkward, use a semicolon. If the second sentence would have a comma after the first word, then use the comma in the semicolon form.’ Now you just need to write a guide for quotes and parenthesis.
Clem Malmborg says on April 7th, 2007 at 12:27 am
When even one list item contains a comma, list items must be separated by semicolons. If this results in clumsy prose, rewrite.
Clem Malmborg says on April 7th, 2007 at 12:33 am
Stephen,
Americans place commas inside quotes, while the British put them outside. The latter makes a lot more sense. To see why, consider the sentence
Type “find -name myfile.txt -print,” then open myfile.txt.
But rules are rules.
Dean says on April 8th, 2007 at 12:14 am
Great tips on writing, you made them really easy to read and understand. I will be trying this out myself.
James E. Lee says on April 9th, 2007 at 1:13 am
Thanks for publishing this! I often feel I use too many commas, semi-colons, and dashes in my writing, and this helps validate doing so. That’s not to say I’ve always been doing it correctly, nor according to the rules above! I look forward to reviewing what I’ve written against these rules, and using them as I continue writing.
jack ryan says on April 9th, 2007 at 11:02 am
NY Times Style Guide and AP style guides says its wrong.
Who is right?
http://www.umw.edu/policies/st.....efault.php
stefi says on April 9th, 2007 at 11:39 am
Hi, as a non native Engligh speaker, I find this information very useful. Thanks
Sergei says on April 9th, 2007 at 5:52 pm
One question: How do you know when to separate two sentences with a semi-colon or simply split them into two separate sentences with a period?
Jeff Carlsen says on April 10th, 2007 at 2:46 am
First, a note on Rule 3: Although I’ve always followed the British standard of placing a comma before the “and”, it’s common practice in the U.S. to omit that final comma. Either is technically correct, though the American way regularly leads to difficulty when the word “and” is used in the middle of a list, such as: In the morning, I shower, shave, brush and floss my teeth and wash my face. The lack of the final comma can confuse things, and certainly alters the flow of the sentence.
For those asking about when to use a semicolon: The only time a semicolon is absolutely necessary is when separating lists of lists. For example: In the morning, I spring out of bed; shower, shave, brush and floss my teeth, and scrub my face; pour a large bowl of milk, cereal, and fresh fruit; eat it; then grab my phone and car keys before heading out the door.
The more common use of a semicolon is to link to directly related complete sentences. In all the examples given above, one sentence draws upon information from the previous, or the two share similar ideas. Know that a semicolon is not required here, but is a stylistic choice. A period is always permitted instead.
Lastly, on the use of dashes: There are three ways of interjecting a thought into a sentence: a coma, a dash, and a pair of parentheses. There are no requirements as to which you must use in any situation, but each has different stylistic effects, based on the importance of the interrupting element. Here’s a simple set of rules:
1. If the interrupting element is of generally equal importance to the meaning of the sentence, use a comma. This is the most common case.
2. If the interrupting element is of more importance than the rest of the sentence, use a dash.
3. If the interrupting element is of lesser importance, or generally unrelated to the point of the sentence, surround it in parentheses.
Examples:
1. You can, and probably should, use commas in most sentences.
2. You can–when you need to draw attention to something–use a dash instead. You can also use a dash at the end of a sentence–like a writing ninja!
3. Sometimes what you want (or been pressured into wanting by an evil overlord (also known as your boss)) to say is completely unrelated to the sentence; in this case use parentheses.
A note on the dash. The symbol for a dash isn’t on the standard Qwerty keyboard. In such cases, use a double hyphen instead. Most programs will recognize this as a dash.
Jeff Carlsen says on April 10th, 2007 at 3:03 am
About commas inside of quotation marks. The comma only goes inside the quotation marks during dialog. This is done because the line of dialog is a complete sentence in and of itself, but you’re still adding the speaker to the end of the sentence. Thus, “You should write a quotation like this,” said Jeff.
In every other case where you use quotation marks, put the punctuation outside the quotations.
In fact, it is not incorrect to put an additional period at the end of a piece of dialog outside the quotes, like this: Jeff said, “This is perfectly within the rules.”. It’s simply standard practice to omit the final period. There are situations where putting that final piece of punctuation is worthwhile, such as with a question or exclamation:
Did Jeff say, “You are allowed to do this.”?
I can’t believe he said, “Go ahead and use two periods.”!
These examples should clearly show what’s happening. The inner period ends the quotation (which is a complete sentence and thus needs a period), while the outer one ends the sentence as a whole. In reference to the origional question, since the word single word isn’t a complete sentence, I don’t put a period after the word “example”. At least, not within the quotes.
Jeff Carlsen says on April 10th, 2007 at 3:04 am
About commas inside of quotation marks. The comma only goes inside the quotation marks during dialog. This is done because the line of dialog is a complete sentence in and of itself, but you’re still adding the speaker to the end of the sentence. Thus, “You should write a quotation like this,” said Jeff.
In every other case where you use quotation marks, put the punctuation outside the quotations.
In fact, it is not incorrect to put an additional period at the end of a piece of dialog outside the quotes, like this: Jeff said, “This is perfectly within the rules.”. It’s simply standard practice to omit the final period. There are situations where putting that final piece of punctuation is worthwhile, such as with a question or exclamation:
Did Jeff say, “You are allowed to do this.”?
I can’t believe he said, “Go ahead and use two periods.”!
These examples should clearly show what’s happening. The inner period ends the quotation (which is a complete sentence and thus needs a period), while the outer one ends the sentence as a whole. In reference to the origional question, since a single word isn’t a complete sentence, I don’t put a period after the word “example”. At least, not within the quotes.
Stephen Long says on April 10th, 2007 at 10:12 am
Came across this quotation:
The older I grow, the less important the comma becomes. Let the reader catch his own breath. Elizabeth Clarkson Zwart
And she still uses a comma!
Matt says on April 13th, 2007 at 2:56 am
I was always told you shouldn’t have a comma before ‘and’.
e.g.
Wine, women, and song.
Would be:
Wine, women and song
Els says on April 13th, 2007 at 9:41 pm
“(Note: In the next-to-last sentence in the previous paragraph, there’s a comma after however because it’s an introductory element in the second sentence.)”
After all the rules about comma’s, shouldn’t there be one more comma in this sentence? I’d say a comma is needed before ‘about’, since the sentences can be switched:
Because it’s an introductory element in the second sentence, there’s a comma after however in the next-to-last sentence in the previous paragraph.
Or perhaps I misunderstood..
Michael Leddy says on May 19th, 2007 at 11:10 am
@Els: A good question, and I’ll admit that I simplified matters in my post. When you switch parts, sometimes a comma is necessary and sometimes not. The best way to judge is to consider whether the element at the end is necessary to the meaning. Consider these sentence-pairs:
Why did you bring an umbrella?
I brought an umbrella because I thought it would rain.
What did you bring?
I brought an umbrella, because I thought it would rain.
In the first exchange, the words “because I thought it would rain” are crucial to the meaning. In the second exchange, they’re not.
I think of this kind of comma as analogous to seasoning — sometimes you need it; sometimes you don’t. With the sentence that you quoted, I don’t think a comma is necessary before because. But I wouldn’t say it’s wrong to include one.
Kelley says on July 14th, 2007 at 8:36 am
I was always told to basically use a comma whenever there needed to be a pause in a sentence. Is this true?
Jason says on July 24th, 2007 at 10:55 pm
No! This is not true at all. It’s usually what people are told because it’s easier than explaining the rules of using commas. You can make a pause in a sentence anywhere just by reading it a certain way. The rules explained above are correct, but a pause is just that — a pause.
Alice says on January 13th, 2008 at 3:37 pm
I wouldn’t take punctuation advice from someone who doesn’t know the difference between “that” and “which,” as in:
“Any element which interrupts…”
And in the U.S., you DO put the comma inside the quotation marks, always, at least according to the Chicago Manual of Style, which (notice the correct use of “which” here) is the authority.
Steve says on February 18th, 2008 at 6:01 pm
@Alice, you live to flame people who are only attempting to help don’t you? Stop acting high and mighty.
@Michael
Great tips, apparently Google was my friend today when it led me here.
Hukito says on April 22nd, 2009 at 10:37 pm
“That” and “which” may be considered interchangeable. However, if one wishes for arbitrary differentiation, “that” is used where none may applicatorily possess the same attributes within context (For example, in the sentence “In my room, I have 2 boxes that are red.”, there cannot be any more than those 2 boxes that are red under this discretionary circumstance, whereas the sentence “In my room, I have 2 boxes which are red.” necessitates 2 boxes with any number succeeding (2 or more red boxes exist).
Also, Axalover seems to typfiy pretense for English knowledge (though it is a common misconception): it is NOT requisite for the usage of a comma; it is necessary only where the object (or other noun) is ill-defined (or perhaps with naught therefor). If a sentence does not have denomination, no comma follows (In the sentence “I have a big, brown box, which is in my room.”, the statement exemplifies the permissible and consistent usage of a comma in the definition of the box as “big” and “brown.” In the sentence “I have a box which is in my room.”, the lack of definition allows for the absence of the comma, for the clause bearing “which” actually defines it within itself.
Gordon says on June 11th, 2009 at 2:49 pm
How do you punctuate a sentence that ends with the acronym U.S.?