Many of you have been asking for help with punctuating between clauses and phrases within sentences. You want to know when you should use a comma and when you need a semicolon. Here are a few rules with examples that I hope you find very helpful.
Commas
Rule: Use a comma between two independent clauses when conjunctions such as and, or, but, for, nor connect them.
Example: I have painted the entire house, but she is still working on sanding the floors.
Rule: If the clauses are short (your call), then leave out the comma.
Example: I painted and he sanded.
Rule: If you have only one clause (one subject and verb pair), you generally won’t need a comma in front of the conjunction.
Example: I have painted the house but still need to sand the floors.
This sentence has two verbs but only one subject, so it has only one clause.
Semicolons
So when does the semicolon get to have its time in the spotlight?
Rule: Use the semicolon if you have two independent clauses you are connecting without a conjunction.
Example: I have painted the house; I still need to sand the floors.
Rule: Also, use the semicolon when you have commas for smaller separations, and you need the semicolon to show a bigger separation.
Example: We had a reunion with family from Salt Lake City, Utah; Los Angeles, California; and Albany, New York.
Pop Quiz
Select the correctly punctuated sentence.
1a. I attend the fashion shows and my husband goes to the jazz clubs. 1b. I attend the fashion shows, and my husband goes to the jazz clubs.
1c. I attend the fashion shows; and my husband goes to the jazz clubs.
2a. I love fashion and he loves jazz. 2b. I love fashion, and he loves jazz.
2c. I love fashion; and he loves jazz.
3a. I attend the fashion shows but not the jazz clubs. 3b. I attend the fashion shows, but not the jazz clubs.
3c. I attend the fashion shows; but not the jazz clubs.
4a. I attend the fashion shows my husband goes to the jazz clubs. 4b. I attend the fashion shows, my husband goes to the jazz clubs.
4c. I attend the fashion shows; my husband goes to the jazz clubs.
5a. I buy cheese, milk, and eggs at my neighborhood market apples, oranges, and grapes from the farmers’ market and aspirin, shaving cream, and deodorant from the pharmacy. 5b. I buy cheese, milk, and eggs at my neighborhood market, apples, oranges, and grapes from the farmers’ market, and aspirin, shaving cream, and deodorant from the pharmacy.
5c. I buy cheese, milk, and eggs at my neighborhood market; apples, oranges, and grapes from the farmers’ market; and aspirin, shaving cream, and deodorant from the pharmacy.
Pop Quiz Answers
1b. I attend the fashion shows, and my husband goes to the jazz clubs.
2a. I love fashion and he loves jazz.
3a. I attend the fashion shows but not the jazz clubs.
4c. I attend the fashion shows; my husband goes to the jazz clubs.
5c. I buy cheese, milk, and eggs at my neighborhood market; apples, oranges, and grapes from the farmers’ market; and aspirin, shaving cream, and deodorant from the pharmacy.
If the article or the existing discussions do not address a thought or question you have on the subject, please use the "Comment" box at the bottom of this page.
Sentences are made up of clauses and phrases. A clause is a group of words that contain at least a subject and a verb (NB: a clause can be a sentence).
There are four sentence types: simple, compound, complex, and compound-complex.
A simple sentence is made up of one independent clause. An independent clause is a group of words, consisting of at least a verb and a noun that can stand alone as a sentence and is a complete idea. A simple sentence may also contain an object. Have a look at these examples:
I saw a psychologist is an independent clause. It contains a subject (I) and a verb (saw), and expresses a complete thought.
Public safety must be the primary concern of any police force is also an independent clause that also includes an object. It contains a subject (Public safety), a verb (must be), and an object (the primary concern of any police force).
A compound sentence is a sentence made up of two or more independent clauses joined together. You can join clauses in two different ways, using a coordinating conjunction or a semi-colon. Coordinating conjunctions consist of the following words: For, And, Nor, But, Or, Yet, So ("FANBOYS"). Have a look at these examples:
Professional athletes train at a higher intensity than other individuals, so they are fitter than them. (conjunction: so)
Public safety must be the primary concern of any police force, and officer training should focus on public safety above all else. (conjunction: and)
Professional athletes train at a higher intensity than other individuals; they are fitter than them. (semi-colon use)
Public safety must be the primary concern of any police force; officer training should focus on public safety above all else. (semi-colon use)
Note the punctuation (commas & semi-colons) used above to separate these independent clauses.
Common Grammatical Errors
- Joining two independent clauses together with ONLY a comma is grammatically incorrect, and is called a comma splice.
- Not using any punctuation or connecting words between independent clauses is also grammatically incorrect, and is called a run-on sentence.
A complex sentence consists of one independent clause and one or more dependent (subordinate) clauses which provide more information to support the independent clause. A dependent clause does not express a complete idea. In a complex sentence there is normally one idea that is more important than the other. Have a look at these examples:
Healthcare professionals are people who are experts in health and are willing to help others. (bold print: independent clause; normal print: dependent clause)
Police force officers are trained in public safety and are expected to maintain law and order is society. (bold print: independent clause; normal print: dependent clause)
- Compound-Complex Sentences
A compound-complex sentence contains at least three clauses. Two of these clauses MUST be independent clauses. You can have any combination of clauses just as long as 2 or more are independent and one or more is dependent. Have a look at these examples:
I could not decide where I should work or what I should do, so at first I did nothing. (bold print: independent clause; normal print: dependent clause; coordinating conjunction: so)
I wanted to travel after I graduated from my studies at ACAP, however, I had to work and save first. (bold print: independent clause; normal print: dependent clause; note that 'however' is not a conjunction)
- Effective writers combine short and long sentences and ensure their written work is clear and easy to understand. In spite of what people may think, using long and complicated sentences is not a sign of academic scholarship. Make sure your writing expresses your points clearly.
Watch a video on fixing sentences with missing parts
What is the ideal sentence length?
Using too many short sentences or sentences that are too long, complicated, or convoluted can significantly mar your written work. Ideally a sentence should be between 15-25 words, however using some slightly shorter or longer sentences can also be effective in your written work.
Watch a video on sentence length and order
I want to know more about sentences!
In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation.
RUN-ON SENTENCES AND COMMA SPLICES
Run-on sentences can be divided into two types. The first occurs when a writer puts no mark of punctuation and no coordinating conjunction between independent clauses. The second is called a comma splice, which occurs when two or more independent clauses are joined by just a comma and no coordinating conjunction.
Example of a run-on sentence:
The flowers are beautiful they brighten the room. (Incorrect)
Example of a comma splice:
The flowers are beautiful, they brighten the room. (Incorrect)
Examples of correct alternatives:
The flowers are beautiful. They brighten the room.The flowers are beautiful; they brighten the room.The flowers are beautiful, and they brighten the room.
The flowers are beautiful because they brighten the room.
A run-on sentence is not defined by its length! The fact that a sentence is very long does not automatically make it a run-on sentence. As you will see, the sentence structure and use of punctuation determine whether a sentence is a run-on.
In order to better understand run-on sentences and comma splices, it is important to review the basics of writing a grammatically correct simple sentence:
| A simple sentence is made up of only one independent clause. An independent clause is a group of words that contains a subject and a predicate and forms a complete thought when standing alone. The subject refers to someone or something (the subject contains at least one noun or pronoun). The predicate refers to what the subject does or is (the predicate contains the verb or verbs). Both the subject and predicate can contain additional descriptive elements, such as adverbs, adjectives, prepositions, or other modifying phrases, but in its most basic form the subject is the part of the sentence that contains the noun, and the predicate contains the verb. |
A sentence can be complete and correct with one basic independent clause made up of one subject plus its corresponding predicate. To demonstrate the basic structure of a simple sentence, find the noun that forms the subject and divide it from the verb.
| Subject | Predicate | Sentence |
| I | am. | I am. |
| The man | studied. | The man studied. |
| A frog | jumped. | A frog jumped. |
| Lola | sings. | Lola sings. |
By dividing the noun and verb, we can add modifiers to a simple sentence and still see the two basic parts, the subject and the predicate.
| Subject | Predicate |
| The man | studied. |
| The kind man | studied hard. |
| The kind man at the library | studied hard for the test on Friday. |
When looking at the structure of an independent clause, it is helpful to think of all elements of the subject separately from all elements of the predicate. Together the subject and predicate form the two basic and separate parts of each clause.
| Subject | Predicate |
| The kind man and his wife | studied hard for the test and read a book. |
| The man, his wife, and their child | studied hard, read books, and ate dinner. |
If the independent clause forms a complete thought, a period at the end demonstrates that the sentence is complete. The period means STOP. The sentence has ended, and a new sentence will begin.
Run-ons and comma splices occur when more than one subject/predicate pair exists in the sentence. When one subject/predicate pair is followed by an additional subject/predicate pair within one sentence (forming separate independent clauses), they need to be separated (or joined) according to very specific rules of punctuation and grammar.
Look at the following example of a run-on sentence:
The kind man studied hard his wife read a book. (Incorrect)
If we divide the sentence into subject/predicate pairs (each an independent clause), we see that two independent clauses exist, one following the other:
| First independent clause | Second independent clause | ||
| Subject | Predicate | Subject | Predicate |
| The kind man | studied hard | his wife | read a book. |
Without the correct separation, the two independent clauses written together form a run-on sentence. Once you can identify a run-on sentence by its incorrect structure, it is not hard to find a way to correct it.
When two independent clauses appear in one sentence, they must be joined (or separated) in one of four ways:
1. The two clauses can be made into two separate sentences by adding a period.
2. The two clauses can be joined by a comma and a coordinating conjunction (comma plus: and, but, or, nor, for, so, yet).
3. The two clauses can be joined by a semicolon.
4. The two clauses can be rewritten by adding, changing, rearranging, or deleting words. The simplest way to accomplish this is to add a subordinating conjunction between the clauses.
Notice that joining the independent clauses by a comma alone is NOT a choice. When two independent clauses are joined by only a comma, this error is called a comma splice.
The table below demonstrates the four correct options. When two independent clauses appear in a sentence, try to imagine a middle column in which only four possibilities exist to join the two clauses:
| First independent clause | Second independent clause | |||
| Subject | Predicate | 4 CORRECT OPTIONS |
Subject | Predicate |
| The kind man | studied hard | . (period) | His wife | read a book. |
| The kind man | studied hard | , and, but, or, for, nor, so, yet (comma plus a coordinating conjunction) |
his wife | read a book. |
| The kind man | studied hard | ; (semicolon) | his wife | read a book. |
| The kind man | studied hard | while afterasbecause . . . (examples of subordinating conjunctions - no comma required) |
his wife | read a book. |
Please note again that in the above examples a comma alone is NOT one of the correct options.
The kind man studied hard, his wife read a book. (Incorrect)
A comma alone between two independent clauses creates an incorrect comma splice.
Summary (Including Related Grammar Rules)
1. An independent clause contains one subject/predicate pair and expresses a complete thought.
Music makes my life worth living.
| Subject | Predicate |
| Music | makes my life worth living. |
2. A simple sentence is made up of only one independent clause:
Music makes my life worth living.
3. A run-on sentence is made up of two or more independent clauses that are not joined correctly or which should be made into separate sentences. A run-on sentence is defined by its grammatical structure, not its length.
Incorrect: My favorite band is in town they are performing now.
Correct: My favorite band is in town. They are performing now.
Correct: My favorite band is in town, and they are performing now.
4. A comma splice is the incorrect use of a comma to join two independent clauses.
Incorrect: I love classical music, it makes me feel joyful.
Correct: I love classical music because it makes me feel joyful.
Correct: I love classical music; it makes me feel joyful.
5. A compound sentence contains two or more independent clauses that are correctly joined by a comma plus a coordinating conjunction or by a semicolon:
Music means a lot to me, and certain songs bring wonderful memories to mind.
| First independent clause | Second independent clause | |||
| Subject | Predicate | Comma and coordinating conjunction | Subject | Predicate |
| Music | means a lot to me | , and | certain songs | bring wonderful memories to mind. |
Music means a lot to me; certain songs bring wonderful memories to mind.
| First independent clause | Second independent clause | |||
| Subject | Predicate | Semicolon | Subject | Predicate |
| Music | means a lot to me | ; | certain songs | bring wonderful memories to mind. |
6. A comma plus a coordinating conjunction can connect independent clauses correctly. There are seven coordinating conjunctions (sometimes remembered by the acronym "fanboys"):
for, and, nor, but, or, yet, so
7. A complex sentence contains one independent clause and one or more dependent clauses. The dependent clause begins with a subordinating conjunction:
I always think of summer whenever they play that song.
| First independent clause | Second independent clause | |||
| Subject | Predicate | Subordinating conjunction | Subject | Predicate |
| I | always think of summer | whenever | they | play that song. |
8. A subordinating conjunction connects a dependent clause to an independent clause. The dependent clause cannot stand alone; it requires attachment to an independent clause in order to express the complete meaning of the sentence. The following are examples of some of the most common subordinating conjunctions:
after, although, as, as if, because, before, even though, if, in order that, rather than, since, so that, than, that, though, unless, until, when, whenever, where, wherever, whether, while
For more information, please see the following TIP Sheets:
Independent and Dependent Clauses: Coordination and Subordination
Sentence Type and Purpose