Fragments are incomplete sentences that have been disconnected from the independent clause (or main clause). Fragments are dependent clauses (or subordinate clauses) because they cannot stand on their own without a subject or a verb. Therefore, fragments do not make much sense. Look at the following:
- Since we have never met before. I shall introduce myself.
- When they arrive. We shall have lunch.
- After he lost the match. The tennis player threw his racquet.
- Because he has never been to this part of town before. He lost his way to my house.
The dependent clauses are highlighted in red. The errors above appear to be too obvious to some of us, but I have seen many of my students making such mistakes in their essays. You can correct fragments by removing the period and substituting it with a comma. So the five sentences above should be corrected as follows:
- Since we have never met before, I shall introduce myself.
- When they arrive, we shall have lunch.
- After he lost the match, the tennis player threw his racquet.
- Because he has never been to this part of town before, he lost his way to my house.
Alternatively, the sentences above could also be written without a comma, but the sentences must begin with independent clauses. See what happens here:
- I shall introduce myself since we have never met before.
- We shall have lunch when they arrive.
- The tennis player threw his racquet after he lost the match.
- He lost his way to my house because he has never been to this part of town before.
As you can see, commas are not needed in each of the four sentences because the sentences begin with a complete sentence (an independent clause) as highlighted in blue. The meaning of each sentence is exactly the same.