When a sentence rambles on an on, you might end up with a comma splice or a fused sentence.
There is not much difference between the two:
You’ll notice these errors particularly if you read the following sentences aloud:
Comma splice: The rain has finally stopped, I think I will go for a stroll.
Fused sentence: The rain has finally stopped I think I will go for a stroll.
Correct: The rain has finally stopped. I think I will go for a stroll.
You can probably hear the break, and when you look closely you’ll notice that there is no conjunction that ties the two clauses together. Each clause is independent (it has at least a subject and a verb), but there is no grammatical connection between them.
Watch out for sentences with a dependent clause. Sometimes the dependent clause has been connected to two clauses instead of one:
Amsterdam is a beautiful city, though I’m not inclined to visit the Red Light district, I thoroughly enjoyed my visit.
Dependent clause: though I’m not inclined to visit the Red Light district.
Correct: Amsterdam is a beautiful city. Though I’m not inclined to visit the Red Light district, I thoroughly enjoyed my visit.
In this case, the middle clause is mistakenly tied to both the first and last clause.
There is one more term that is sometimes used to describe these mistakes. It’s the phrase run-on sentence.
Unfortunately, there is little agreement about what constitutes a run-on sentence. For some people the term refers to any time two clauses are joined without a coordinating conjunction (so both comma splices and fused sentences), whereas others limit it to just fused sentences. Others use it indiscriminately whenever they feel a sentence goes on a bit too long.
For the sake of clarity we will just talk about comma splices and fused sentences.
There are three easy ways to fix comma splices and fused sentences. Here they are, starting with the most common solution.
1. Simply put in a period (as in the example above).
2. Use a semi-colon if you think the clauses are closely related.
3. Connect the clauses with a conjunction.
If you decide to use a conjunction (the last solution), you’ll have to decide if the clauses have equal weight. If they do, you can use a coordinating conjunction:
The rain has finally stopped, so I think I will go for stroll.
If, on the other hand, you want to make one clause more important than the other, you can use a subordinating conjunction:
Since the rain has finally stopped, I think I will go for stroll.
It’s all a matter of emphasis.
When the main clauses in a sentence are very short, you can often get away with a comma splice. Here’s an example:
I love your dress, it’s so pretty.
This is not recommended in formal prose, but it’s not uncommon in creative writing, especially in dialogue.
Probably the biggest cause of comma splices is the incorrect use of conjunctive adverbs. These are words like however, moreover, and although. They connect separate sentences rather than two parts of the same sentence:
According to Swiss folklore, William Tell was an expert with a crossbow, in fact, he not only shot an apple off the head of his son, but he also assassinated the man who had ordered him to do so.
Conjunctive adverb: in fact
To fix this sentence you’ll have to insert a period or a semi-colon before the conjunctive adverb. If you want some further instruction on how to recognize this problem, please review the rules for conjunctive adverbs.