Grammar teachers hate them. Writers use them to good advantage. What? Pieces of sentences that lack something—a subject or verb—to make them complete.
Fragments help pace. Sometimes you want the reader to stop. Abruptly. And pay attention to one word. Like I did with “abruptly.”
Other times you don’t want to bore the reader by spelling out needless words. For example, “What are sentence fragments?” in the place of “What?”
Fragments serve to break a thirty or forty-word sentence into bite-sized pieces. Years ago, people used commas and semi-colons to do this. Horrors! No editor or publisher wants to see a semi-monster anymore.
Consider the following paragraph:
Rodney kept coming. Full steam. Unstoppable. Like a freight train with a hundred cars and no engineer. No brakeman. No dead-man switch. Except me. If he doesn’t switch off, I’m dead.
This paragraph comprises two sentences with six fragments sandwiched between. You wouldn’t want to bite into it with a stream of connecting commas drooling out of your mouth. Nor would you want me to insert verbs into each fragment to satisfy the palate of your critique group’s strict grammarian.
No, tastes fine as is. (Translation: It tastes fine just as it is.)