I have to admit my googling netted me a disappointing catch on this one. I was hoping that some grammar geek had compiled a list of at least the most common introductory words, but alas, this does not seem to be the case.
Introductory words can take several forms, but in all cases they are not necessary for meaning in the sentence. They’re an extra. And extras, whether words, phrases, or clauses, are set off from the rest of the sentence when they come at the beginning of the sentence. Some are not set off when they come later–for more information, read my posts on introductory clauses and phrases.
Common introductory words are adverbs, interjections (including affirmation or negation–most commonly yes and no), and I’m going to throw names used as address in there as well, even though they’re set off no matter where they occur.
- Introductory adverbs need to be set off from the rest of the sentence with commas, UNLESS they are part of a part of a phrase, in which case the entire phrase gets a comma. Common examples are however, meanwhile, suddenly, finally, besides, and still. These are often used as transition words, to link one sentence to the next. I was able to find a site with a list of these (although it doesn’t list them all), and it even breaks them down by category: https://www.msu.edu/user/jdowell/135/transw.html#anchor1782036. Common examples include:
- However, the rent was still past due.
- Meanwhile, the soon-to-be ex-husband had hired a lawyer.
- Suddenly, she was left with a stack of bills to pay and no way to pay them.
- Still, there was always the revolver in the closet.
- Besides, was it absolutely true that crime never pays?
Be careful, though, that you don’t just mechanically put a comma after every adverb when it begins a sentence, or worse, every time it occurs at all. Make certain first that it isn’t part of an introductory phrase, or even another phrase entirely.
- However she juggled the bills, the rent was still past due.
- Suddenly poor, she was still left with a stack of bills to pay besides the rent.
2. Interjections are often used for emphasis. I was able to find a partial list of them here: http://www.yourdictionary.com/index.php/pdf/articles/156.listof-interjections.pdf. This list is very incomplete, but it will certainly give you an idea of the types of words that belong. Common ones include please, thanks, yes, no (and all the variations on those like definitely or negative), words that express elation or dismay like hallelujah or drat, and even words that aren’t really words at all like um, uh, achoo, ah, and oh. These get set off with commas.
Note that most profanity belongs here as well. I’m certainly not going to list profane words, but when they are used for emphasis and not as part of a phrase, they, too, are set off with commas.
- Damn, that’s good. (As opposed to: That’s damn good.)
Interjections are set off no matter where they occur.
- Yes, I will, thanks.
- Well, I wanted to go to the store, but, uh, the dog ate my money.
- Amen, brother!
- I looked in the the bathroom, and bingo, found my keys.
- That was terrible. I mean, ugh.
- Ha, that’ll be the day.
- Ouch, that hurt.
- You know, like, wow.
- Oh, no.
The last examples brings me to a final point. When you stack interjections, they should really all get commas. Personally, I think it looks funny, so I try to avoid it. You can break the sentence or use an em dash instead (within reason, we need to ration them).
- Ah, well, I suppose I can go later.
- Oh, no, I’ll never make it in time.
- Yes, thanks, that would be lovely.
- Oh, shoot, that wasn’t supposed to happen.
In all the examples above (except for possibly the second), you could easily lop off the initial interjection and let it stand with only the second. I know people really talk this way, but in my opinion, you want to minimize it in written dialogue. I’d go ahead and leave the second example as is, but I’d be careful not to use another very soon, unless it’s a device for making a particular character’s speech distinctive.
3. Names (and words that function like names, most often insults) always get set off with commas when they’re used as a form of address. The most common place is at the beginning or the end of the sentence.
- Jane, I swear if you leave the door open one more time, I’ll scream.
- Will you please do the dishes, sweetheart?
- Look, wise guy, sarcasm isn’t always an art form.
- It’ll be a cold day in hell before I agree, you mangy son of a dog, and that’s final.
And finally, when you stack interjections and names, they both get set off with commas.
- Oh, Jane, please don’t leave.
- No, Frank, I won’t steal for you.
- Sorry, Charlie, but them’s the breaks. (Yes, it’s ungrammatical, but you should punctuate it correctly anyway.)
I hope this was helpful; the comma is a tricky little thing. I know there are some variations due to house style (some places are no longer setting off trailing adverbs with commas), but you’ll never be wrong if you use these rules.