Comma, Semicolon, or Period – How to Use Each Correctly

A comma, a semicolon, and a period (full stop in British English) have one thing in common. They all represent pauses in speech. However, in writing, they do much more than that. These three punctuation marks are not interchangeable, but one might choose to use a semicolon instead of a period on occasion. Rules guide the use of all punctuation marks in English. Unfortunately, even many native speakers are unfamiliar with these rules.

Why Be Concerned About Punctuation

Suppose you are studying English as a second or foreign language for the sole purpose of verbal communication. In that case, punctuation may not interest you. Speaking is spontaneous. Once the words are out, you can’t take them back or change them anyway. However, with writing, you have the opportunity to go back and review and correct what you have written. If your study includes reading and writing, you should know the following.

When to Use a Comma ( , )

There are several rules you must follow in using commas. These rules can sometimes be complicated. However, your writing will be more readily understood and flow better with practice. Let’s look at the rules with some examples.

Some Simple Rules for Using Commas

1. Use a comma after each word, phrase, or clause in a series of three or more.

• I bought hotdogs, hamburgers, and potato chips for the barbeque.
• He had a shower, had breakfast, and left for work.
• She wasn’t excited about the trip, having to leave her family, and living out of a suitcase.

2. Use a comma after each equal adjective except the last one in a series of two or more describing the same noun. This rule also applies to adverbs describing the same verb.

• It was a long, cold, lonely night waiting in the airport for our connecting flight.
• She has beautiful, long, curly hair.
• It was an unexpected, traffic-halting, torrential downpour.

3. Use a comma after “yes” or “no” at the beginning of the sentence in response to a question.

• Yes, I’ll go shopping with you.
• No, he’s not my type.
• Yes, we have two dogs and three cats.

4. Use a comma after transition words or phrases at the beginning of the sentence. Place a comma before and after the transition if it appears in the middle of the sentence.

• He was the oldest child. Therefore, he had added responsibilities.
• He was a handsome guy, however, without much of a personality.
• I was hungry. Nevertheless, I couldn’t eat raw fish.

5. Use a comma when addressing a person.

• Jill, it’s time to leave now.
• I think, Trevor, that I’d better drive.
• You’re just so full of yourself, Eric.

6. Use a comma before direct quotations.

• Harry said, “I’m having a hard time breathing.
• “Get out,” she said, “or I’m calling the cops.”
• “The concert was late getting started but well worth the wait,” she gushed.

7. Use commas for dates, addresses, and titles.

• He was born on April 18, 1972.
• I live at Unit 13, 7215 Ocean Drive, Oakland, CA 19832.
• Jonathan Howard, MLA for Powel River, proposed the bill in parliament.

That Pesky Oxford Comma

The comma just before the “and” in number 1 above is optional and is called the Oxford comma. We use it in situations where there may be confusion. However, many people think you should always use the Oxford comma in that position. Then, there is no need to worry about confusion. It’s a very controversial and even contentious topic. As you can see from the examples in number 1 above, I am a proponent of always using a comma in that position.

Definitions

Before we look at these more complicated rules, we have to understand a few words of vocabulary:

• independent clause – a clause that could be a complete sentence on its own but is part of a more complex sentence itself; a complete thought
•  coordinating conjunction – a word that joins two equal grammatical functions; in this case, two independent clauses
•  dependent clause – a clause that is not a complete sentence; needs an independent clause to complete the sentence; not a complete thought
•  subordinating conjunction – a word or phrase that joins a dependent clause and an independent clause
•  relative clause – a type of dependent clause, sometimes called an adjective clause; gives more information about a noun; begins with a relative pronoun
•  relative pronoun – introduces a relative clause

Some Not-So-Simple Rules for Using Commas

8. Use a comma before a coordinating conjunction to join two independent clauses.

• I was tired, but the movie kept me up late.
• The exam is tomorrow, and I’m beginning to panic.
• I don’t feel like cooking, so let’s go out to eat.

9. Use a comma after a dependent clause beginning with a subordinating conjunction if an independent clause follows it. Do not use a comma if the independent clause comes first.

• Because he was very good at his job, he got a promotion and a big raise. (comma)
• He got a promotion and a big raise because he was very good at his job. (no comma)
• Despite being very small compared to the others, he easily won the wrestling match. (comma)
• He easily won the wrestling match despite being very small compared to the others. (no comma)

Please note: There is never a comma before a subordinating conjunction if it comes in the middle of the sentence. That includes the word “because”.

10. Use commas to enclose nonessential relative clauses (not necessary to the sentence’s meaning).

• My brother, who lives downtown, constantly complains about everything. (comma)
• The blue car, which is very old, is in my parking spot. (comma)
• John, who is very overweight, is leaving on vacation tomorrow. (comma)

11. Do not use commas to enclose essential relative clauses (necessary to the sentence’s meaning).

• The students who were arrested last night will be expelled. (no comma)
• The man who lives across the street was called to testify in the robbery. (no comma)
• The house on the corner that is so run down will be demolished tomorrow. (no comma)

12. Use a comma anytime it is needed to avoid confusion.

The Annoying and Grammatically Incorrect Comma Splice

A comma splice is when two independent clauses are joined only with a comma. There are three correct solutions to resolving the comma splice:

• Split it into two separate sentences with the appropriate punctuation, usually a period at the end of each sentence,
• Put a semicolon in between the two independent clauses, or
• Follow number 8 above using a coordinating conjunction preceded by a comma.

Under no circumstances can a sentence ever end with a comma.

Semicolon – the Mystery of Punctuation ( ; )

Most native English speakers have no idea how to use a semicolon. I would go so far as to say that the vast majority of native English speakers will go through their entire lives without ever once using a semicolon. The semicolon adds variety and sophistication to your writing if used sparingly. However, you probably don’t feel comfortable using a semicolon if you haven’t taken a writing or advanced grammar course. It’s not difficult to use if you know how.

1. Use a semicolon to connect two closely related independent clauses.

• She went shopping; she bought nothing as usual.
• He took a cab; his car was in the repair shop.
• I was in an accident; our car is totalled.

2. Use a semicolon in a series of three or more instead of a comma (rule number 1 under comma) if the items are long or contain internal punctuation.

• On our vacation, we went to Fairmount Hot Springs, BC; Banff, AB; and Swift Current, SK.

3. You can use semicolons with conjunctive adverbs. These include but are not limited to, moreover, nevertheless, however, otherwise, therefore, then, finally, likewise, and consequently.

• The movie was so boring; finally, it’s over.
• I blew the transmission in my car; consequently, I’m looking for a ride to work.
• I hope it’s not raining tomorrow; otherwise, I’m just staying home.

Period or Full Stop – King of Punctuation ( . )

I call the period or Full stop the king of punctuation because most sentences end with a period. When to use a period is pretty straightforward. Let’s look at some basic rules and examples.

1. Use a period at the end of a statement (declarative sentence).

• The boy was riding his bike.
• The mother duck was leading her babies across the road.
• It was a beautiful day, so we went to the beach.

2. Use a period at the end of a sentence that gives an instruction or command (imperative sentence).

• Shut the door.
• File these papers when you have time.
• Give these to your mother.

3. Use a period at the end of an indirect question.

• My mother wanted to know why I came home so late.
• In court, the criminal asked for forgiveness from the victim.
• Dad wants to know when you’ll be home for dinner.

4. Leave a single space only after a period.

The above essay is for entertainment and English language study only. For suggestions on how to use this post to improve your English reading and listening comprehension, click here.

Resources

• Grammarly Blog – Rules for Comma Usage
• Purdue University – Extended Rules for Using Commas
• 15 Rules for Using a Comma
• Indiana University East
• ESL – Subordinating Conjunctions
• Accurate English