by Sentenceworks
Comma
A comma is just a tiny little mark, but it separates thoughts and ideas so the reader can understand which parts of the sentence are connected to other parts, and to give a nice flow to the sentence. When reading aloud, a reader will pause briefly (perhaps taking a breath) at the comma.With Subjects and Verbs
A comma should not separate a subject from its verb. Separating the subject and its verb with a comma is a mistake generally made if the subject clause is long. Clearly identify the subject of the sentence (what the sentence is about) and its verb (action word). The subject may already have a verb in it, as part of the relative clause.
Incorrect: The things which cause me joy, may also cause me pain.
The subject of this sentence is “the things which cause me joy”, and its verb is “may cause”. A comma is not required in this sentence.
Correct: The method of ensuring you are driving on the right route is to check your G.P.S.
The subject of this sentence is “the method of ensuring you are driving on the right route”, and its verb is “is to check”.
Exception: The only time you may separate a subject from its verb is if the verb from the subject clause is repeated.
Correct: He who offends me, offends me greatly.
Between Two Nouns in a Compound Subject or Object, or Between Two Verbs in a Compound Predicate
Don’t separate two nouns in a compound subject, nor two verbs in a compound predicate, with a comma. There can be more than one subject or object in a sentence, and more than one verb in a predicate.
Incorrect: The twins, and their mother went shopping for shoes for school.
The subjects of this sentence are “the twins” and “their mother”.
Incorrect: Mark despaired both finding a job, and having a decent place to live.
The verbs in this predicate are “finding” and “having”.
Correct: Flowers and candles can pleasantly decorate and scent a room.
The objects are “flowers” and “candles”, and the verbs are “decorate” and “scent”.
Comma Splices
If two independent clauses are to be joined into one sentence, they must be separated by a conjunction or a semi-colon. They may also be separated into two sentences by a period. Use of a comma causes a comma splice.
Incorrect: Koala bears are not actually bears, they are marsupials.
The two independent clauses, “koala bears are not actually bears” and “they are marsupials” should be separated by a semi-colon.
Incorrect: I am not angry with you, I am not happy with you, either.
The two independent clauses, “I am not angry with you” and “I am not happy with you” could be separated into two sentences by a period, or they could be joined with a conjunction, such as “but”.
Exceptions:
Comma splices may be used for artistic or poetic effect, as when one is connecting several short independent clauses:
Correct: She was beautiful, she was gorgeous, she was ravishing.
Comma splices may also be used if the two independent clauses are somehow contrasting, as when following a statement with a question:
Correct: You are coming to the party, aren’t you?
Commas After Introductory Clauses
Introductory clauses are dependent clauses which are found at the beginning of the sentence (although they can be moved to the end of the sentence, too, without confusing the meaning of the sentence). After a dependent introductory clause, we use a comma to separate the introductory clause from the independent clause. The dependent introductory clause may start with an adverb or conjunction like “although”, “if”, or “when”.
Incorrect: As the man was walking into the store he came face-to-face with his childhood sweetheart.
A comma is required between “store” and “he”, because the introductory phrase is dependent.
Correct: Because the rain was torrential, the day’s Little League games were postponed.
The introductory clause, “because the rain was torrential”, requires a comma after it to separate it from the independent clause.
Comma After Conjunction in Introductory Clause
Introductory clauses frequently begin with a conjunction (“although”, “since”, “when”, “if”, etc.) There should be no comma after the conjunction in the introductory clause.
Incorrect: Because, it was going to rain, we cancelled the picnic.
The comma after “because” should be removed; the comma after “rain” is properly used as it separates the introductory clause from the independent clause.
Incorrect: After, flunking her Victorian Literature class, Martha decided to do the assigned reading.
The comma following “after” separates the conjunction (after) from the rest of the introductory clause. The comma should be removed.
Missing comma after introductory clause with date
Introductory clauses which include a date should certainly be offset by a comma.
Incorrect: In 1989 he graduated from high school.
A comma is required between “1989” and “he”, because the introductory phrase is dependent.
Incorrect: By the 1960s most households had a television set.
A comma should be inserted between “1960s” and “most”.
Correct: During the 1800s, canned foods were becoming popular.
The comma after “1800s” is correct because it is separating an introductory phrase from the independent clause.
Commas After Introductory Phrases
An introductory phrase is like a clause, but it does not have its own subject and verb; it relies on the subject and verb in the main clause. Unless the phrase is very short (fewer than 5 words) and begins with a preposition (to, for, at, etc.), there should be a comma between the introductory phrase and the main clause.
Incorrect: Fighting against reason Martha decided to pull an all-nighter in hopes of passing the exam.
The introductory phrase, “fighting against reason”, requires a comma after “reason”.
Correct: By flashlight we made our way along the path.
Because the introductory phrase, “by flashlight” is short and begins with a preposition, a comma is not required.
Commas After Introductory Words
After an introductory word, we use a comma to separate the introductory word from the independent clause. The introductory word in the sentence will frequently be an adverb.
Incorrect: Meanwhile the cat stretched luxuriously in the sunshine.
There should be a comma after the introductory word “meanwhile”.
Correct: Furthermore, the educational institution will prosecute those individuals who plagiarise the institution’s written works.
“Furthermore” requires a comma after it, as it is an introductory word.
Comma Within a Comparison
A comma should not be used within a comparison (unless there is a non-restrictive clause). Frequently, writers will put a comma before a conjunction as this is where speakers will naturally pause for emphasis; when writing, the pause is considered grammatically incorrect. Clearly identify the two things which are being compared and ensure they are not unnecessarily separated by a comma.
Incorrect: This box is lighter, than that box.
The comma after “lighter” should be removed so it does not separate the two items – the boxes - which are being compared.
Incorrect: The box containing the hardcover books is really quite heavy, while the box containing the paperbacks is relatively light.
The comma after “heavy” is not required and should be removed.
Correct: The box on the table, which contains the hardcover books, is really quite heavy while the box containing the paperbacks is relatively light.
This sentence is correct because the commas are being used around the non-restrictive clause, “which contains the hardcover books”.
Comma Use Around “Interrupters”
When we use an “interrupter” in the middle of the sentence, it should be emphasised with commas. Without the use of commas, the flow of the sentence may be awkward for the reader. Some “interrupters” are: in fact, to say the least, however, generally speaking, and unfortunately.
Incorrect: Queen Victoria was as they say a formidable woman.
The interrupter, “as they say”, should have a comma before and after it, to emphasise its separation from the rest of the sentence.
Incorrect: Having demonstrated a decided lack of ethics, the CEO was needless to say dismissed from the company.
The interrupter, “needless to say”, should have a comma before and after it.
Run-on Sentences, Case 1
When two independent clauses are joined by a co-ordinating conjunction (e.g. and, but, or, so), there must be a comma before the conjunction or it will be a run-on sentence.
Incorrect: Matthew went to the library and I headed back to the science lab.
The two clauses, “Matthew went to the library”, and “I headed back to the science lab” are independent; a comma should be inserted before “and”.
Incorrect: The wind was brisk but the sun was strong.
The two clauses, “the wind was brisk”, and “the sun was strong”, are independent; there should be a comma before “but”.
Correct: The man’s business was failing, so he was searching for alternative income.
The two clauses, “the man’s business was failing” and “he was searching for alternative income”, are independent. The co-ordinating conjunction, “so” requires a comma before it.
Run-on Sentence, Case 2
An independent clause is a clause which could be a sentence all by itself (it contains both a subject and a predicate), but is put together with another clause. If two independent clauses are put together, they must be separated so the reader is clear which subject belongs to which predicate.
Incorrect: Mustard is good on greens ketchup is good on hotdogs.
As this is a relatively informal sentence, the independent clauses could be separated by a conjunction and a comma: Mustard is good on greens, while ketchup is good on hotdogs. Use of a semi-colon would also be correct.
Incorrect: There are many benefits to eating organic food the benefits are both physical and psychological.
The independent clauses could be separated by a comma and a conjunction (…eating organic food, and the benefits…), or by a semi-colon (…eating organic food; the benefits…). They could also be turned into separate sentences with a period.
Missing comma before a question tag
When we have a statement which we want someone to agree with, we add a few words on the end, turning it into a question. These few words are called, “question tags”. These are words like “isn’t it/he/she” or “right”, or even “yes”or “no”. These question tags should be separated from the main clause by a comma.
Incorrect: The citizens of the world all want clean water do drink do they not?
“Do they not” is a question tag. It should be separated from the statement by a comma: The citizens of the world all want clean water do drink, do they not?
Incorrect: Legends about werewolves, vampire and other monsters from are considered to be some of the scariest stories around no?
In this sentence, the single word, “no” is used as a question tag. Grammatically, this sentence is incorrect (and, therefore, difficult to understand) unless the “no” is separated from the main clause by a comma: Legends about werewolves, vampire and other monsters from are considered to be some of the scariest stories around, no?
Punctuation of Appositives
Use commas properly when using an appositive.
An appositive is a noun or pronoun (perhaps with some adjectives, etc.) which adds extra information to clarify a noun in the sentence. Take this sentence, for instance: My mom Angela is a good cook. “Angela” is the appositive for “mom”. If the appositive is not necessary to understand the sentence, there should be commas around the appositive. If the appositive is necessary to understand the sentence, don’t put commas around it.
Incorrect: A brilliant young painter the artist was given his own show at the age of 19.
The appositive, “a brilliant young painter” is not required to understand this sentence; there should be a comma after “painter” (but not at the beginning of the appositive, as it is at the beginning of the sentence).
Incorrect: The professor, Dr. Kendrick, was a wonderful teacher.
The appositive, “Dr. Kendrick”, is necessary in order to understand which professor was a wonderful teacher, so there is no need for commas around it.
Correct: The rose, a deep red blood drop, stood out amongst the tiny white flowers.
Because “a deep red blood drop” is not necessary to understanding what the rose was doing, commas are required on either side of the appositive.
Comma in dates
When writing a date, a comma is used to separate the day from the month, and the date from the year.
Incorrect: The American Declaration of Independence was ratified on July 4 1776.
A comma is required between the date and the year: July 4, 1776.
Incorrect: I was born on Sunday May 12 1968.
The date requires a comma between the day and the month, as well as between the date and the year: Sunday, May 12, 1968.
Correct: Please come to the Open House on Monday the 12th.
Because the month is not specified and there is an article between the day and the date, no commas are required in this sentence.
Correct: The application is to be finished by 31 December 2009.
Although inappropriate for use in formal writing, this format does not require any commas.
Comma between coordinate adjectives
When one has several co-ordinate adjectives (i.e. a list of adjectives which do not have to be in any particular order), a comma is used to separate them. This is done for clarity and emphasis.
Incorrect: That man is a pompous self-righteous annoying idiot.
As it doesn’t matter which order these adjectives are in, a comma should separate them: That man is a pompous, self-righteous, annoying idiot.
Incorrect: The sweet scintillating aroma of cinnamon buns filled the kitchen.
Because sweet and scintillating can be used in any order, there should be a comma between them.
Correct: The adorable little boy was eating ice cream.
In English, we usually put little and boy together, so the two adjectives (adorable and little) do not require a comma between them.
Unnecessary comma in a complex sentence
Complex sentences are sentences which have two clauses. There can be two independent clauses (each having a subject and predicate), or an independent clause and a dependent clause (missing a subject or predicate). Generally, if the dependent clause comes second, a comma is not used before the dependent clause. Frequently, but not always, a conjunction will begin the dependent clause.
Incorrect: I need to do the shopping, because there is nothing to eat in the house.
The second clause, because there is nothing to eat in the house, is dependent; there is no need to use a comma between the two clauses.
Incorrect: It makes no sense to study Advanced Pure Math, if the student will not use the math at a later date.
The dependent clause, if a student..., does not require a comma before it.
N.B.
If the sentence is too long or confusing without a comma, one may be used for purposes of clarity.
Correct: In the background of the painting there are a boat, a river, and a sunset, which attract the viewer’s attention.
Here, a comma is used before the dependent clause because otherwise the reader may think only the sunset attracts the viewer’s attention.
Comma Between Compound Subject and Predicate
A compound subject is a subject which lists more than one thing. Commas may be used within the compound subject to separate the nouns, but should not be used between the subject and the predicate of the sentence.
Incorrect: Some frequent causes of headaches are, stress, lack of exercise and dehydration.
The comma between “are” and “stress” should be removed because it separates the predicate from the subject. The other comma is grammatically correct.
Incorrect: Literacy and good writing skills, are necessary in most careers.
The comma in this sentence should be removed. No commas are required in this sentence.
Comma in Compound Predicate
A compound predicate is a predicate which has two parts. Let’s look at this sentence: Mary likes chocolate and caramel. The subject is “Mary”. The predicate is “likes chocolate and caramel”; because it has two parts (chocolate and caramel), it’s called a “compound predicate”. Words like “and” and “or” will help identify a compound predicate. If there are only two ideas in the compound predicate, they do not need to be separated by a comma. If there are more than two ideas, the comma should be used as it would in a list.
Incorrect: The purpose of a comma is to clarify lists, and conjoin ideas.
The compound predicate, “is to clarify lists and conjoin ideas”, does not require a comma. The comma should be removed.
Incorrect: This dog is young, but well-trained.
“Is young but well-trained” is a compound predicate. It does not require the comma before “but”.
Correct: The dog is young but well-trained and good-natured.
This sentence does not need a comma as the conjunctions separate the ideas in the compound predicate.
Correct: The dog is young, well-trained and good-natured.
The comma in this sentence is correctly placed as it is being used to clarify the elements in a list.
Missing Comma in a List
When creating a list of two or more things, commas should be used to separate each category in the list. There is no formula for this; you must use logic and reason understand the categories. Some sentences use several verbs, so the commas will separate the items which belong to a different verb. Some items can be separated by adjectives.
N.B. Frequently, errors of this nature occur between the last two items, so look before the “and”.
Correct: I cleaned the house and the garage, raked the lawn, and took out the garbage.
The list in this sentence categorises items by verb. Some readers will insist the comma after “lawn” is unnecessary but without the comma the reader will be looking for another item which was being raked: I…raked the lawn and ___.
Incorrect: Mary bought the shirt in red, purple, and black.
This sentence doesn’t need a comma before the “and” because the three colours refer to the shirt Mary bought. The final comma should be removed.
Incorrect: For the bouquet of roses, I selected three red ones, three white ones and two black ones.
Here, the categories are being defined by the numbers and colours of roses. Because “two black ones” is a different category than “three white ones”, there should be a comma before the “and”.
Missing comma in series (within list of similar elements)
When creating a list or series of multiple things, commas should be used to separate each item in the list.
N.B. Frequently (though not always), errors of this nature occur between the last two items, so look before the “and”.
Incorrect: Teenagers are often anxious to grow up get a job and move out of their parents’ house.
This sentence is missing two commas. If you look carefully, there are three things teenagers want to do: 1) grow up, 2) get a job, and 3) move out of their parents’ house. A comma should be inserted after “grow up” and “get a job”, to separate the items in the list.
Incorrect: I still have to buy a gift pack the suitcases, and arrange for someone to water the plants while we’re at the wedding.
This sentence is missing a comma after “gift”.
Separating Verb and its Object
A verb (action word) should not be separated from its object (the thing or person which is receiving the verb). To figure out what the object of the sentence is, ask yourself this: what is the subject doing? Let’s look at the sentence, “Mary likes chocolate”. The verb is “likes”, so we would ask, “what does Mary like?” She likes chocolate, so the object of the verb is “chocolate”.
Incorrect: The teacher claimed, she was too busy to help her students outside of class.
To find the object of the verb, we ask ourselves “what did the teacher claim?” The teacher claimed she was too busy to help her students, so there should be no comma separating “claimed” from “she was too busy to help her students”. The comma should be removed from this sentence.
Incorrect: After finding her classes’ grades were slipping, the teacher decided to stay, for an extra hour after school each day.
Our question for this sentence would be “what did the teacher decide?”: the teacher decided to stay for an extra hour. The comma after “stay” should be removed from the sentence. The comma after “slipping” is correctly placed as it separates a dependent clause from an independent clause.
Setting Off Non-restrictive Clauses
A restrictive clause is a clause which limits a subject; this might be something identifying, such as the colour of a person’s hair, or the position of a book on a table. A restrictive clause may use the word “that”, and cannot be removed from the sentence without loss of information.
A non-restrictive clause is a clause which may offer more information, but doesn’t limit the subject; this might be something of interest, such as how old something is or a job a person has. A non-restrictive clause may use the word “which” and can be removed from the sentence without loss of understanding.
Non-restrictive clauses are generally separated from the rest of the sentence by commas, while restrictive clauses are not.
Incorrect: That box of apples which I picked this morning can be used to make the pie.
The non-restrictive clause, “which I picked this morning”, should have a comma on either side of it. This information is not required to identify the box.
Incorrect: Three years ago, the house on the corner which was of historical interest was torn down.
The non-restrictive clause, “which was of historical interest”, should have a comma on either side. This information is not required to identify the house.
Setting Off Restrictive Clauses
Incorrect: The box of apples, that has the red label on it, can be used to make the pie.
The restrictive clause, “that has the red label on it”, should not have a comma on either side of it. The label is required to identify the box.
Incorrect: Three years ago, the house, on the corner, was torn down.
The restrictive clause, “on the corner”, should not have a comma on either side. The information is required to identify the house.
Between Correlative Conjunction Sets
Correlative pairs of conjunctions include words like, “neither..nor”, “not…but”, and “both…and”. For this punctuation rule, we can also consider sets of words like “not only…but also”. When pairs or sets of conjunctions are being used, they do not need to be separated from each other by a comma. However, a comma may be used between the conjunctions to accommodate another grammar rule (see “exceptions”).
Incorrect: Either the blue shirt, or the red sweater will look good with your jeans.
“Either…or” is a correlative pair of conjunctions. The comma should be removed from this sentence so the conjunctions are not separated from each other.
Incorrect: I can’t decide whether to have pizza, or a cheeseburger.
In this sentence, “whether…or” should not be separated by a comma.
Exception: If two commas are around a non-restrictive clause, they may be used between the correlative pairs of conjunctions.
Correct: Neither the job as a cashier, which only paid minimum wage, nor the washroom attendant’s job interested the woman with two PhDs.
Emphasising Contrasting Ideas With Commas
A group of words which offers a contrast to the subject of the sentence may need to have a comma on either side to separate it from the main idea. Look for words such as “not”, “unlike” and “never”; these signify a contrasting idea. By putting a comma on either side, the contrasting idea is made clear to the reader, and the subject is clearly modified.
Incorrect: Mary unlike Ann is very organised.
Written like this, the reader assumes “unlike” is modifying “Mary”. The contrasting idea, “unlike Ann”, should have a comma on either side of it to separate it from the main idea: Mary, unlike Ann, is very organised.
Incorrect: Tea should be steeped not boiled.
Without a comma separating the contrasting idea from the main idea, the reader may read: Tea should be boiled not. A comma should be inserted between “steeped” and “never”: Tea should be steeped, not boiled.
Correct: Most people will continue wanting, but rarely needing, more and more material objects.
“But rarely needing” is a contrasting idea, so it is appropriately offset by commas.
Between Direct Quote and Attributive Tag
When quoting, it must be made clear to the reader who said (or wrote or thought) whatever is being quoted; this is done by using “attributive tags”. Look for words like “he said”, “he claimed” and “according to”. Attributive tags can be at the beginning or end of the quote, or even in the middle (in which case you would use a comma before and after the attributive tag). American convention generally places commas outside opening quotation marks and inside closing quotation marks.
Incorrect: At the end of the class the professor remarked “How attentive you have been today!”
To separate the attributive tag from the quote, a comma should be inserted between “remarked” and the beginning of the quote: …the professor remarked, “How attentive….”
Incorrect: “There is a problem” the head caretaker agrees “with the storage of garbage between pickups.”
In this sentence, the attributive tag “the head caretaker agrees” is in the middle of the sentence. There should be a comma between “problem” and the quotation mark, and another comma after “agrees”: “There is a problem,” the head caretaker agrees, “with the storage of garbage between pickups.”
Correct: “You have ice cream on your nose,” my friend snickered.
This sentence is correctly punctuated with a comma between the quote and the attributive tag.
Comma After Question Mark
We usually use a comma to separate a quote from an attributive tag (e.g. “he thought”, “said he”), even if the quote would usually end in a period. However, if the quote is a question, a question mark needs to be used in order to show the reader that the sentence is a question. If there is a question mark, there is no need to use a comma as well; in this case, the attributive tag should come immediately after the closing quotation marks. The same rule applies to exclamation points, which are required if the reader is to understand the tone the speaker is using.
Incorrect: “Do you want to come to the movies with us?”, Mary asked.
The comma between the quote and the attributive tag is not required, and should be removed.
Incorrect: “I am trying to sleep here!”, my roommate yelled.
The comma before “my” should be removed, as the exclamation point adequately separates the quote from the attributive tag.
Correct: My roommate yelled, “I am trying to sleep here!”
This sentence is correctly punctuated because the attributive tag is at the beginning of the sentence; the comma is used to separate the attributive tag from the beginning of the quote so there is no conflict between two punctuation marks.
Comma Before Parenthesis
Parentheses are used to give additional information to the reader: information which is not required and which would disrupt the flow of the sentence if written as a non-restrictive clause. Commas may be placed after the closing parenthesis but not before either the opening or the closing parenthesis. If the sentence would not require any commas if the parentheses were removed, the sentence should not have any commas when the parentheses are added.
Incorrect: After opening the new cookie tin, (and eating several of the cookies), Mary had a hard time replacing the lid.
The comma after “tin” should be removed. The comma after the closing parenthesis is correctly used as it separates a dependent clause, (after opening the new cookie tin) from an independent clause (Mary had a hard time replacing the lid) .
Incorrect: After opening the new cookie tin (and eating several of the cookies,) Mary had a hard time replacing the lid.
The comma after “cookies” should be placed after the closing parenthesis.
Incorrect: Peter cleaned his room, (grumbling all the while,) before going out to play basketball.
This sentence does not require any commas; both should be removed.
Comma Between An Article And Its Noun
Commas are used to separate thoughts or ideas, or to tell the reader when to pause. Articles are used to refer to a noun, so the article can’t really be a separated from the noun as it’s all part of the same idea. The articles in English are “the”, “a” and “an”. Nouns are a person, place or thing.
Incorrect: The company managers accidentally scheduled the, weekly meeting for Saturday.
The comma between “the” and “weekly” should be removed because it separates the article “the” from the noun “meeting”.
Incorrect: A, bouquet of flowers may be created using more than one type of flower.
The comma between “a” and “bouquet” should be removed.
Incorrect: I’ll have an, apple.
When speaking, we will often pause while we think of the next word. While a speaker may pause after an article, it is not a grammatically correct pause; when written down, there should be no comma after “an”. Generally, this example will not come up in formal writing but if it should, the pause can be indicated with an ellipsis: “I’ll have an… apple.”