The comma (,) sets off or separates words or groups of words within sentences. Commas are the most common punctuation mark inside a sentence. However, the trend today is to use them only when absolutely necessary, or when omitting the comma would cause confusion.
Use a comma after a long introductory phrase or clause: “After working all day at the office, I went home for dinner.” If the introductory material is short, forget the comma: “After work I went home for dinner.”
Use a comma if the sentence would be confusing without it, as in: “The day before, I borrowed my boss’s calculator.”
Use a comma to separate elements in a series, including numbers in a list: “I enjoy drinking orange juice, tea, milk, and coffee.” You also use it with numbers: “5, 7, and 9.” (There are some style guides that omit the comma before “and,” but you’ll notice that we like it. The important thing is to make sure that you are being consistent, and that you use what your organization is using.)
Use a comma to separate independent clauses that are joined by and, but, or, nor, for, or yet. “We shopped for three hours, but we didn’t make a single purchase.”
Use commas to set off nonessential elements in a sentence. Compare these two sentences:
- In this sentence: “At the podium stood a man wearing a green suit,” the phrase “wearing a green suit” is essential to identify which man.
- However, in this sentence: “At the podium stood Frank, wearing a green suit,” the phrase “wearing a green suit,” adds nonessential information about Frank.
You can also use a comma to:
- Separate a city or town from a state or province, as in Sarasota, Florida and Ferntree Gully, Victoria.
- Set off the name in a direct address, as in, “Jane, can I please see you in my office?”
- After dates, when day, month, and year are used, as in, “He was born Thursday, August 12th, 1975.”
- Before degrees that come after a name, as in Joan Walker, PhD.
- Set off an informal quotation, as in: Robert remarked, “My investment counselor is very good.”
- After linking adverbs such as however, therefore, etc. “The hike was several miles long; however, the path was a good one.”
- Separate thousands in numbers for clarification, as in 18,239.
When shouldn’t we use commas?
- Do not use commas between two independent sentences.
- Do not use commas after titles like Jr. or Sr.
- Do not use a comma after a month when only the month and the year are used.
Note: If you use words like however, moreover, therefore, consequently, nevertheless, or then between two independent clauses (i.e., sentences by themselves), you must use one of the following:
- A period
- A semicolon
- A comma plus a conjunction between the two clauses
NOT, “It looked difficult, therefore, we did not try.”
- BUT, “It looked difficult. Therefore, we did not try.”
- OR, “It looked difficult; therefore, we did not try.”
- OR, “It looked difficult, and therefore we did not try.”
A semicolon (;) separates two independent clauses, but it keeps those two thoughts more tightly linked than a period can: “I type letters; he types bills.”
The semi-colon sometimes raises people’s blood pressure, but it is a very useful punctuation mark. A semi-colon has three important features:
- It is considered a more defined pause that the pause required by a comma.
- It is used to separate major sentence elements of equal grammatical rank.
- It is used to separate sentences joined by logical conjunctions such as however, therefore, thus, and nevertheless.
Example: “I learned all the rules and regulations; however, I never really learned to control the ball.”
It can also be used to separate two closely related sentences not joined by a conjunction. The semi-colon in this instance is useful for showing contrast or balance.
Example: “Having more work to do is relatively easy to bear; what stings is having more to do than everyone else.”
It should also be used to separate a series that is complicated or whose items contain internal punctuation (such as commas).
Example: “Please direct your comments to one of these individuals: Pat Warner, chair of the committee; Ross Ingram, public affairs; or Calvin Jenkins, promotions.”
Use a semicolon before an a comma after the following words if the words come between two independent clauses:
Examples:“I thought I had completed the project; consequently, I was surprised to hear about the additional work.”
- “We have prepared your estimate; however, you should sign it by Friday.”
- “The partner’s retreat will be held in March; therefore, all business matters will be discussed then.”
A colon (:) is a tip-off to get ready for what’s next: a list, a long quotation, or an explanation. It’s used to separate independent clauses when the second clause explains or amplifies the first.
- “Fred was proud of his sister: she had been promoted to managing partner.”
- “My new office contains the following items: a partner’s desk, a leather chair, and oak paneling.”
- “We need additional information: escrow statements, tax returns, approved bank loans, and mortgage agreements.”
- “There are two things to remember in a job interview: always arrive promptly, and always dress appropriately.”
Other common uses include:
- After the formal salutation in a business letter
- Before a list
- To separate hours and minutes (depends on culture)
An apostrophe (‘) is commonly used to form the possessive of nouns and some pronouns, and to mark the omission of letters in a contraction.
Use an apostrophe when the meaning of “it’s” is “it is.” (Using it’s when the word does not mean “it is” is one of the most common mistakes in the English language!)
Note that it’s never correct to use an apostrophe in a possessive version of its. This means that anytime you see “its” with an apostrophe after the s, it is incorrect.
Use an apostrophe to show singular possession (“The doctor’s office was always busy”) and plural possession (“The doctors’ offices were always busy”).
Note: The use of an apostrophe can be determined by inserting an of phrase, as in “The offices of the doctors were busy.”
If the noun is singular, add “s”:
- “I enjoyed Betty’s presentation.”
- “Someone’s coat is in the lobby.”
The same applies for the singular nouns ending in “s,” like James: “This is James’s new office.”
Use an apostrophe to show possession of two objects by two people. “Hilda’s and Janet’s cars were crushed by the falling tree.”
Use only one apostrophe when a possession is shared by two people. “Robert and Susan’s house sold in five hours.”
Use an apostrophe to show possession in words that are already plural. “The women’s changing room at the gym was being renovated.” Or, “The men’s changing room had been renovated last year.”
Use an apostrophe to show contractions. “They’re on vacation and can’t get back in time for the meeting.”
Use an apostrophe to show plural of lower case letters. “I made sure that I dotted all my i’s and crossed all my t’s before I signed the contract.”
Use an apostrophe to show possession in a single compound noun. “We are living in my mother-in-law’s house until ours is finished.”
Use an apostrophe to form the possessive case of indefinite pronouns. “This election could be anyone’s win.”
Use an apostrophe in expressions of time or value: two weeks’ notice, two dollars’ worth of nuts.
Spelling Tips and Tricks
Here are some tips for making your documents the best that they can be:
- Use a dictionary. It doesn’t matter which form you use, but it is important that you be consistent.
- Use spell check on your computer, but don’t rely on it totally since it often misses incorrect homonyms.
- Use the Internet or a telephone book to check spelling of names and addresses. However, there are sometimes errors in these sources, too. If you are not sure, simply call the office of the person you are contacting and ask.
- Proofread your work, and when possible, have someone else proofread your work.
- Learn some little tricks to help you remember words that you use frequently but still spell incorrectly, like “i before e, except after c.”
- Make a list of your most common spelling errors and learn how to spell those words correctly. Keep that list posted so you can refer to it when you need to.