This week, we’re going to discuss the correct usage of colons [:] and semi-colons [;]. Despite their similarity in name and appearance, these punctuation marks cannot be used interchangeably. Each has its own unique role in the English language.
Semi-colons are primarily used to join two independent clauses. Using a semi-colon is an alternative to using a comma followed by a conjunction or breaking the independent clauses into separate sentences. The semi-colon provides a hard break while also suggesting that the two clauses are closely-related:
I had ESL class at the English Island in Atlanta today; the lesson covered the differences between colons and semi-colons.
You can also use a semi-colon with a transition:
I planned to deposit my check on the way home from work; however, the bank was closed by the time I arrived.
Do not use a semi-colon with a conjunction:
I planned to deposit my check on the way home from work; but the bank was closed by the time I arrived. (Incorrect)
Either replace the semi-colon with a comma or remove the conjunction:
I planned to deposit my check on the way home from work, but the bank was closed by the time I arrived.
I planned to deposit my check on the way home from work; the bank was closed by the time I arrived.
Semi-colons can also be used to separate items in a list when each item itself contains multiple commas:
John wore black, flat front slacks; a pressed, pinstripe shirt; and a slim, navy tie.
Colons are used to announce lists, noun phrases, direct quotations, examples, and explanations. The key to correct colon usage is to remember that the information that comes after the colon must describe/explain what came before the colon in some way.
With a series or list:
The class will cover several types of punctuation today: colons, semi-colons, commas, and dashes.
The list after the colon gives examples of “types of punctuation.”
With a noun phrase:
The English Island gave me the tools I needed to succeed: confidence and experience.
The “tools” are “confidence and experience.”
To introduce a quotation:
When I’m tempted to speak ill of someone, I remember my mother’s favorite saying: “If you can’t say something nice, don’t say anything at all.”
Because the quotation is introduced with a full sentence, the introduction and quotation must be separated with a colon.
To provide an explanation:
My father has a unique talent: the ability to truly understand people.
“The ability to truly understand people” is the “unique talent” that the father of the speaker possesses.