Run-ons and comma splices | Syntax | Khan Academy

Hello Grim, Marians. Hello Rosie. Hi David, how are you? Good, how are you? Good.

Today we are going to talk about run-ons and comma splices. A run-on sentence is what happens when two independent clauses are put together in one sentence without any punctuation or coordinating conjunctions like and, but, and, or, so. Rosie, what is a good example of a run-on sentence?

We bought Nails, we bought a hammer. Yeah, so we can see that this sentence contains two individual independent clauses. So we've got number one: we bought Nails. Number two: we bought a hammer. Now, there are a couple of different ways we could make this a legal sentence, but right now, as it stands, this is a run-on, right?

So there are a couple ways we could fix this sentence. One way would be just to add a semicolon in there: semicolon. So you've got two independent clauses: we bought Nails; semicolon we bought a hammer, right? Another way you could do that would be to just add a comma and then the conjunction and, so you're connecting those two clauses.

So this is a run-on sentence without this and and this comma. And it's called that because it's sort of like a runaway train, right? You know, it doesn't have enough stoppage in it. That's how I would put it. So that's what a run-on sentence is.

And now I want to talk about comma splicing. The word splice is not a super common term if you are neither a sailor nor a film editor. But splicing is a word that originally meant to take two ropes, untangle them, and weave them back together. It's a sailor's term related to rope lines. In our case for grammar, a splice—a comma splice—is an inappropriate joining of two independent clauses by using a comma.

So, Rosie, this is Lil Tony, crime-fighting Pony, right? So for example, in this sentence: I love Lil Tony: 2 Pony up to the streets, it's my favorite movie in the Lil Tony franchise—a very fine series of non-existent films. The problem with this sentence is that right now it's got this comma in the middle of it, and this comma inappropriately joins these two independent clauses.

Oh, and this whole time I forgot to say: two independent clauses inappropriately joined by a comma. So, okay, we’ve got independent clause number one—remember this thing could stand on its own as a sentence: I love the name of this movie. I love Lil Tony: 2 Pony up to the streets; that could be its own sentence on its own. End it with a period: period. It's my favorite movie in the Lil Tony franchise: period.

But we have these two independent clauses, right? We cannot join them with just a comma. We could say: I love Lil Tony: 2 Pony up to the streets, comma, and it's my favorite movie in the Lil Tony franchise. Or, as we did in the previous example, we could also throw in a semicolon, which is, I think, what I would rather do: I love Lil Tony: too Pony up to the streets; semicolon. It's my favorite movie in the Lil Tony franchise.

And Rosie, you will notice that I have underlined these titles. Oh yes, because these are the names of published works, right? Even though we made them up, exactly. But okay, for real, I would love to see a Lil Tony crime-fighting Pony series.

So to review: when you're looking at a run-on, you're looking at two independent clauses that are together in one sentence that are joined inappropriately without punctuation or conjunctions. So we bought Nails, we bought a hammer. There's not really a place to know where the division between clauses is in that.

And so the thing to do is to either add some kind of—add a comma and a conjunction or to combine them using a semicolon. The same deal with a comma splice is just that a comma splice is a run-on that hasn't been fixed all the way, right? The comma is being used, but we need some bigger punctuation in place of the comma, something like a semicolon, in order to make a distinction between those two independent clauses.

So that is how you identify and fix run-ons and comma splices. You can learn anything. David out! Rosie out!