Colons

I've seen quite a few colons posing as semicolons and semicolons posing as colons, but the two aren't interchangeable. While the semicolon is commonly used to separate ideas within a sentence, the colon is used to introduce something. It acts as a pointer of sorts to whatever is coming next, which could be a list of some kind, a direct example, or a quote.

Contrary to popular belief, I play three instruments: the spoons, the nose flute, and the buffoon.

It acts as a pointer of sorts to whatever is coming next: a list, a direct example, or a quote.

When you're using a colon to introduce a list, one thing to keep in mind is maintaining the list's structure. It should retain its list-nature all the way through.

Contrary to popular belief, I play three instruments: the spoons, the nose flute, and sometimes after a hard day, the buffoon.

The sentence is evil now because it includes more than just the list of instruments. That sometimes after a hard day phrase is contaminating the former purity of the list.

Using a colon to simply introduce something that isn't a list couldn't be more straightforward.

There's one thing I can never remember about my sister-in-law: her name.

Introducing a quote with a colon is fairly undemanding, too. Just add your quote.

Mrs. Robinson was proud of her photograph, and said so: "I always told him that fruit flies like a banana, and now I have proof!"

In a recent interview, Dr. Robert's attorney seemed evasive: "I would simply indicate that I can neither confirm nor deny your allegations."

If you ever find yourself in doubt over whether to use a semicolon or a colon in a sentence, there's a simple test. If you remove the semicolon and replace it with a period, you should still have two good sentences. Short sentences maybe, but grammatically correct. On the other hand, replacing a colon with a period won't result in two good sentences if you were using the colon to introduce a list or an example. If you were using it to introduce a quote, you'll just have the introductory sentence on one side of the period, and the quote all by itself on the other.