Commas

Commas are important to the writing process. They separate words and groups of words within sentences, allowing each word to stand out as its own idea. Although commas are common forms of punctuation, there are many rules for how they should be used in writing.

When should you use commas?

A series is a set of three or more elements within a sentence. Commas are used to separate each of these elements.

*Note: When (and) separates the last two words or phrases in a series, the comma precedes (and).

Examples

• Thomas owns a red car, a green car, and a white car.
• Penny’s dog eats lots of food, spends most of his time playing, and enjoys chewing shoes.

Commas can be used to highlight an introductory phrase at the beginning of a sentence. Following an introductory phrase, a comma is placed to separate the phrase from the rest of the sentence.

Examples

• Rather than writing her paper, Jane decided to watch a movie.
• Initially, scientists thought the sun revolved around the earth.

Commas separate transitional phrases from the rest of a sentence. Unlike introductory phrases, commas can separate transitional phrases at the beginning, middle, or end of a sentence.

Examples

• Additionally, water is healthier than soda because it does not contain sugar.
• Unlike dogs, cats, of course, do not like water.
• Robert received a good grade in math, thankfully.

Commas separate nonrestrictive clauses from the rest of a sentence, highlighting the additional information. Commas are unnecessary in restrictive clauses.

Nonrestrictive clauses are unnecessary clauses in a sentence. This means that they can add some emphasis to an idea, but they are not required to complete the sentence. In a nonrestrictive clause, the first and last parts of the sentence (outside the commas) can form a complete sentence without the information in the nonrestrictive clause.

Restrictive clauses are clauses that are necessary clauses in a sentence. Without the restrictive clause, a sentence would lose its meaning.

Examples of Nonrestrictive Clauses (with commas)

Babe Ruth, a famous baseball player, was skilled at hitting home runs.
In this example, the nonrestrictive clause is the statement, “a famous baseball player,” because this is “extra” information that is not necessary to make the sentence a complete sentence.

Running, although it can be painful, helps people improve their health.
In this example, the nonrestrictive clause is the statement, “although it can be painful.”

Examples of Restrictive Clauses (without commas)

• Sally enjoys going to the beach to play in the ocean.
• Learning how to write is an essential skill.

In dates, commas are needed to separate the day of the week from the month and day, and they are needed to separate the month and day from the year. A comma does not need to be used to separate the month and day.

*Note: In a sentence, if the date is not at the end of a sentence, there needs to be a comma following the year.

In addresses, commas are used to separate the street address and the city, and they are used to separate the city and state. There is no comma between the state and the zip code.

Examples of commas in dates

• My brother’s birthday was Tuesday, March 2, 2021.
• On April 22, 2020, Americans celebrated Earth Day.
• The fire drill is scheduled for March 8.

Examples of commas in addresses

• The University of Lynchburg is located at 1501 Lakeside Dr, Lynchburg, Virginia 24501.
• The famous author used to live in Vermont, but he moved to 231 Grove Street, Brentwood, Tennessee.

Similar to nonrestrictive clauses, commas separate appositives from the rest of the sentence.

An appositive can be a single word or a group of words. Appositives refer to nouns or pronouns by renaming, describing, or identifying them in a sentence.

Examples of commas in appositives

Michael Phelps, a famous swimmer, has won numerous gold medals.
In this sentence, the noun is Michael Phelps, and the appositive is the phrase, “a famous swimmer.”

A wealthy businessman, he began his successful company at the age of 14.
In this sentence, the pronoun is “he,” and the appositive is the phrase, “a wealthy businessman.”

When are commas not required?

Incorrect example: Anna’s husband bought her, flowers, chocolates, and a stuffed animal for Valentine’s Day.

The comma preceding “flowers” is incorrect.

Correct example: Anna’s husband bought her flowers, chocolates, and a stuffed animal for Valentine’s Day.

Incorrect example: Bobby, Billy, Jim, and Jane, ran in a race.

The comma after “Jane” is not required.

Correct example: Bobby, Billy, Jim, and Jane ran in a race.

Incorrect example: While attending a baseball game, Ryan, caught a homerun.

The comma after “Ryan” is incorrect. “Ryan” is the subject, and caught is the verb. Thus, there does not need to be a comma.

Correct example: While attending a baseball game, Ryan caught a homerun.

Incorrect example: Riding horses is fun, and scary.

The comma preceding “and” is incorrect. The phrase, “Riding horses is fun,” is an independent clause, but the word, “scary,” is a dependent clause. The coordinating conjunction is “and.”

Correct example: Riding horses is fun and scary.

Incorrect example: Basketball, and baseball are both sports.

In this sentence, basketball and baseball are subjects that are both described by the ending phrase of the sentence. This means they are compound subjects. A comma should not separate the two subjects.

Correct example: Basketball and baseball are both sports.

Incorrect example: It has been raining, a lot, all day.

In this example, the phrase, “a lot,” should flow directly with the rest of the sentence. It does not need to be separated out by a comma.

Correct example: It has been raining a lot all day.

Additional Rules About Commas

Commas must be used to separate each item in the list.

The comma must precede the conjunction.

Commas need to follow dependent clauses and prepositional phrases.

A comma is required.

Commas are required if the quotation occurs at the beginning or middle of the sentence, but they are not required if the quotation ends the sentence.

Commas are not required when a quotation ends with a question mark or an exclamation point, even if the quotation occurs at the beginning or middle of a sentence.

If a quotation is at the beginning of a sentence, the comma follows at the end of the quote, and it must be inside quotation marks.

If a quotation is in the middle of a sentence, there must be a comma before the quotation (outside quotation marks) and after the quotation (inside quotation marks).

Commas may not be required between each word; however, if the adjectives are interchangeable or can be separated by the word “and,” then a comma is required.

Examples:

• The big, red kite flew into a tree.
• The long, copper earrings dangled from her ears.

A direct address to someone or something – Commas are required.

Examples:

• No, cats are not better than dogs.
• Cindy, can you get me a cup of coffee?

Semicolons

Semicolons are often used to link related ideas in a sentence.

When should you use semicolons?

Sometimes, two independent clauses are related, but there are no connecting words to link them together. In this case, a semicolon is needed. You can think of the semicolon as a “connector” between two independent clauses.

Conjunctive adverbs are often used to link two independent clauses, and they require the assistance of a semicolon. A few conjunctive adverbs are indeed, consequently, also, however, therefore, moreover, and hence. When semicolons are used with conjunctive adverbs, the semicolon precedes the conjunctive adverb, and a comma follows the conjunctive adverb.

Semicolons are required when you create a list or series within a sentence, and each part of the series uses a comma.

Sometimes, two independent clauses are joined with a coordinating conjunction (for, and, but, etc). If such clauses are especially lengthy or contain commas, a semicolon is necessary to link these two clauses. When this occurs, the semicolon directly follows the first independent clause, and a comma directly follows the coordinating conjunction.

Colons

A colon is a type of punctuation that consists of two equally sized circles that are centered on the same vertical line.

When should you use colons?

Colons are used to introduce a list.

Note: a colon is used when listing, but there must be a complete sentence or an independent clause before the listed items.

Colons are used to introduce a single item.

Colons are used to introduce an explanation.

Colons are used to introduce speech.

Note: You should capitalize the first letter of the first word of a complete sentence that is a quotation when it follows a colon.

Colons are used between independent clauses when the second sentence explains, illustrates, paraphrases, or expands on the first sentence.

Colons are also used to show the time.

Note: A colon is used to separate the hour and minutes when expressing the time. Also, there should not be a space before or after the colon.