On the one hand, the comma is apparently the most popular punctuation mark in English; on the other hand, it is often misused.
These are the uses of the comma you should know:
v To separates items.
Examples:
1. He bought shirts, jackets, trousers, socks, and shoes.
2. The names on the list were: Olusola Adeboye, Leon James, Uchechi Anazodo, Usman Rabiu, Polinosky Sanzer and Kim Kardashian.
See explanation on comma before ‘and’.
v Used in larger units to separate phrases, clauses and sentences.
Examples:
1. The boy, according to the report, was about nine years old at the time of his abduction.
2. That was his reaction when he saw her coming towards him, but he could not confront her, at least not immediately.
3. His wife is the best thing that has happened to him, she is the best thing anyone could ask for.
Note: commas can replace a semicolon or even a full stop (as in 3 above).
v In quotation.
Examples:
1. He looked around and said, ‘The world is really in trouble.’
2. My problem is not your business,’ he said furiously.
Rules: If information about the speaker precedes the expression, the comma stays outside the quote (as in 1); if not, it stays outside (as in 2).
However, commas are used twice if information about the speaker interrupts the expression.
Examples:
1. ‘I know for sure,’ she added, ‘what we need is not a new teacher.’
2. ‘That was the end of it,’ he opined, ‘ I don’t expect anything else.’
Note: Single quotation marks (‘ ‘) are preferred in British English, double (” ”) are preferred in American English.
Other uses
v It is imperative to know that comma can be used with a particular word in a context but omitted in another. For examples, when ‘however’ means ‘on the other hand’, ‘in contrast’ or ‘despite that’, use a comma after it.
Examples:
1. However, we must listen to their fallacy to improve on our argument.
2. Thomas was nervous when he got to the podium. However, he sang beautifully until the crowd gave him a standing ovation.
When it means ‘in whatever way’, don’t use a comma.
Example:
1. However you want it, we’re willing to help.
v When the omission of a word or group of words does not affect the meaning of a sentence, use commas to set it apart.
Example:
1. My stand, so you’d know, is that deregulation is overrated.
Note: The group of words within the commas above is an extra information that will not affect the sentence meaning if removed.
v When addressing someone, use a comma to separate the name from the rest of the sentence.
Examples:
- Dennis, check the date on the receipt.
- What’s the battalion’s ETA, Sergeant?
- We are, sir, the best of them all.
v When you use introductory words in a sentence, use a comma after them.
Examples:
- Oh, that was a good one!
- In fact, most of the books were published after his retirement.
- On the contrary, I was not informed about his demotion.