Punctuation
Commas
Comma Splices
Definition: This error occurs when a writer links two independent clauses with a comma instead of a conjunction.
Examples:
-
Incorrect: “Mako sharks speed through the ocean, they can swim at speeds over 30 miles an hour.”
-
Correct: “Mako sharks speed through the ocean, and they can swim at speeds over 30 miles an hour.” OR “Mako sharks speed through the ocean; in fact, they can swim at speeds over 30 miles an hour.” OR “Mako sharks speed through
the ocean. They can swim at speeds over 30 miles an hour.”
Oxford Commas
Definition: An Oxford comma is the comma placed just before the conjunction in a list of three or more entries (words, phrases, or clauses).
Examples:
-
Incorrect: “I ate plums, peaches and papayas.”
-
Correct: “I ate plums, peaches, and papayas.”
Commas With Names and Titles
Definition: Use a comma around a name if the name is not crucial to the sentence’s meaning. Do not use a comma around a name if the name is crucial to the sentence’s meaning. Place a comma before a name if the name comes at the end of the sentence. Use commas when naming cities, states or countries; when writing dates; or when using titles. When writing ‘jr.’ or ‘sr.,’ there are several options to consider. Either put the comma only before 'jr.' or 'sr.' or around them.
Examples:
-
Names: “I purchased coffee for my friend, Sandra.”
-
Locations: "San Antonio, Texas."
-
Dates: "June 14, 1998."
-
Titles: "José Altuve, Ph.D."
-
Jr./Sr.: "Martin Luther King, Jr., wrote 'Letter from Birmingham Jail.'"
Commas and Coordinating Conjunctions
Definition: The list of coordinating conjunctions is easy to recall with the acronym FANBOYS. The acronym stands for these conjunctions: for, and, nor, but, or, yet, so. When joining two independent clauses, place a comma after the first clause and before the coordinating conjunction.
Example: “I didn’t want to study grammar rules, so I procrastinated.”
Commas Between Adjectives
Definition: Typically, writers place commas between coordinate adjectives—that is, between adjectives that equally modify a noun (neither adjective assumes a superior role in modifying the noun). A writer can generally determine if adjectives are coordinated by using two rules. The first rule is that if the writer flips the order of the adjectives and the sentence still makes sense, the adjectives are coordinated. The second rule is that if a writer can mentally insert ‘and’ between the adjectives in place of the comma, the adjectives are coordinated. If these rules do not apply, the adjectives are non-coordinate, and the writer does not need to place a comma between them.
Examples:
-
Coordinated adjective: “An evening sky is a vast, colorful expanse.”
-
Non-coordinated adjective: “An evening sky is a vast orange expanse.”
Commas With Introductory Word Groups
Definition: Use a comma after an introductory word, phrase, or clause.
Examples:
-
“Finally, he mowed the lawn.”
-
“After dark, the family watched the stars.”
-
​“Before you leave, please take out the trash.”
Other Comma Rules
Semicolons
Definition: Use a semicolon between independent clauses with associated meanings. Use a semicolon between associated independent clauses, joined by a transition. Use semicolons when listing entries that already contain commas.
Examples:
-
Independent clauses with associated meanings: “She rode the bus; she had forgotten to pick up her Buick from the repair shop.”​
-
Independent clauses joined by a transition: “She had forgotten to pick up her Buick from the repair shop; therefore, she rode the bus.”
- ​List entries that already contain commas: “As she shopped, she selected blueberries, which contained vitamins; kale, which contained minerals; and roasted​ chicken, which contained proteins."
Colons
Definition: Use a colon before giving an entry or entries. Do not use a colon in this manner if the sentence would normally require no punctuation where the colon is placed. Colons can also be used before quotations.
Examples:
-
Before an entry or entries:
-
“Don’t forget what I told you: to sleep.”
-
“Please bring these books: a dictionary, a Norton Anthology, and a thesaurus.”
-
-
Use a colon before a quotation such as this one: “Grammar rules are difficult.”
Hyphens
Dashes
Definition: Grammarly suggests that writers should place a hyphen (-) between compound modifiers. Also use hyphens for words such as “sister-in-law” (plural: “sisters-in-law”) or “thirteen-year-old.”
Example: “He ran about the room in a coffee-induced mania.”
En Dash
Definition: Use an en-dash (–) to indicate concepts such as time ranges or game scores. Writers can also use an en-dash when a sentence has two hyphenated elements or uses a complex-compound adjective.
Examples:
-
Time range: "40–50 years,"
-
Game score: "The Packers beat the Eagles 32–24."
-
Two hyphenated elements: “my great-aunt’s hippy–era outfits,”
-
Complex-compound adjective: “Hellenistic Period–architectural types,”
Em Dash
Definition: Use an em-dash (—) to replace commas for stylistic emphasis. The writer could replace the parentheses with em-dashes. You could also use an em-dash to replace a colon to achieve purposeful stylistic stress.
Examples:
-
Replace commas: “The movie theater—stained and dilapidated—frightened me.”
-
Replace parentheses: “The team players—every single one of them—loved Coach Calhoun.”
-
Replace a colon: “He found what he needed—a cup of caffeine.”
​