- Commas may be needed to set off a nonessential description. For instance, when I refer to “my grandson Jasper,” there is no comma between “grandson” and “Jasper” because if I just said “my grandson,” you wouldn’t know which of my three grandsons I was talking about. If I only had one grandson, I could set it off with commas because I could take that name out of the sentence and it wouldn’t change the meaning. If I was saying something about “President of the United States, Barack Obama,” the comma is OK because if you deleted his proper name, you would still know who I was talking about. If it doesn’t change the meaning of the sentence to take it out and the sentence still makes sense, use commas. If you need that language for the sentence to make sense, take the comma(s) out.
- With dates, the proper rule is to set off the year in complete dates with commas. “He started on February 23, 2011, in his new position.”
- Just because serial commas are correct does not mean that every time the word “and” appears, it should have a comma in front of it.
- A comma’s intent is not to be used each time you would take a breath or pause in reading the writing. While that may be a good guide, it is not a good rule.
- Some words are always preceded and followed by commas:
- i.e. (that is)
- e.g. (for example)
- etc.
- et al. (when it follows two or more names)