Colons and semicolons look a lot alike, but they are not siblings in the family of punctuation. They are probably not even first cousins. They are hardly ever interchangeable. They have entirely different purposes. Actually, the semicolon is more a sibling to the comma, and maybe a first cousin to the period. The colon might be an only child and perhaps a first cousin to the period also.
My sensitivity to this issue began when I was giving some information to someone who was putting a catalogue together, and my name was in it. She said, “So I put your name and then a semicolon, and then the information about you. .” NO. You need a colon. You can’t just throw in any old punctuation mark. The semicolon does not belong in such a place.
So, what is the different between colons (:) and semicolons (;) ?
A colon introduces something. It has a relationship to what follows it. Often it introduces a list, whether the list is vertical or horizontal. A colon can also introduce a quote in a sentence. And occasionally you can use a colon (as you might also use a semicolon, but in different circumstances) to separate two parts of a compound sentence instead of using a period, or a comma and a conjunction. However, if you use a colon in this way, it implies that the second part of the sentence (after the colon) is either a result of or follows from the first part of the sentence. Here are some examples of these ways to use colons:
1.The following colors are among my favorites: blue, purple, and pink.
2. These are the ingredients for the cake:
- Baking powder
3. The mayor made this promise in front of the city council: “We will do everything we can this year to extend the hours that the library is open.”
4. The meeting is crucial and you should attend: we will be discussing raises and promotions.
The semicolon connects things rather than introduces them. They are really “stronger” commas. They can separate two closely related sentences if you don’t want to use a conjunction with a comma. They can separate items in a series that already have commas within them. They can separate the two parts of a compound sentence that already has a series or two that could complicate its meaning. Here are examples of these ways to use a semicolon:
1. I am taking a trip to Asia; my husband doesn’t fly, so he is staying home.
2. The guests included Diane Timmons, a noted artist; the museum curator; Joe Wall, an art critic; and Professor Smith, an art history instructor at the local college.
3. Last year I traveled to Mexico, Canada, the southern part of the United States, and Argentina; and France, Italy, and Greece are in my plans for next year.
You could not substitute a colon for a semicolon in those examples – or vice versa.
If you are doing some type of catalogue or list or dictionary, entries should be followed by a colon, not a semicolon:
Apple: A round, red fruit
Coconut: A tropical fruit with white meat inside
Orange: A thick-skinned fruit containing Vitamin C
And obviously you cannot substitute a semicolon for the other places you would use colons:
- Digital Time: 3:45
- Between title and subtitle of a book when writing the title in context: The Red Dog: The Story of Amos
- The salutation of a business letter: Dear Mr. Plante:
There you have it . . . Cousins, maybe. But the semicolon and the colon are different animals.