A fragment is an incomplete sentence punctuated as if it were a complete one. Sentences express complete thoughts; fragments do not.
Writers occasionally use fragments for expressive effect in fiction or informal writing. In academic writing, however, fragments undermine the writer’s credibility because they imply an ignorance of basic English grammar.
Two Types of Fragments
Phrase Fragments are grammatically incomplete, lacking either a subject or a verb.
Just walked up and asked the lady for directions.
The wrecked car burning on the freeway and attracting attention for miles around.
(Note that –ing verbs can never be the main verb of a complete sentence.)
Subordinate Clause Fragments are logically incomplete. They begin with a word (a subordinating conjunction) that makes the reader expect more information than the fragment provides. The subordinator prevents the clause following it from expressing a complete thought.
While I was waiting for the morning bus to pick me up.
As she drove to work one glorious summer morning in her new car.
Here are a few common Subordinating Conjunctions:
after, although, as, because, if, since, though, unless, until, when, while
How to Correct Fragments
Fragments are errors of grammar. To fix them, you’ll need to change the sentence itself, not just its punctuation. There are three ways to correct fragments.
1) Supply the missing subject or verb
A Phrase Fragment needs either a subject or a verb. If you provide the subject or verb, you’ll have a complete sentence.
The wrecked car burned on the freeway and attracted attention for miles around.
Henry just walked up and asked the lady for directions.
2) Remove the Subordinator
A Subordinate Clause Fragment magically turns into a sentence when you remove the subordinating conjunction.
WhileI was waiting for the morning bus to pick me up. AsShe drove to work one glorious summer morning in her new car.
3) Make the fragment part of another sentence
You can also fix a Subordinate Clause Fragment by fulfilling the expectation created by the subordinator.
While I was waiting for the morning bus to pick me up, I worked on a crossword puzzle.
Lucy sang along with the radio as she drove to work one glorious summer morning in her new car.
The third option, incorporating a fragment into another sentence, is usually the most elegant way to correct a fragment.