Sentences are essential to conveying any message. By definition, a sentence requires at the very least a subject and a verb. Lacking either one, turns what was intended to be a complete idea into a piece of one, a fragment, nonsense.
The fix? Adjust your syntax to make it into a stand alone sentence or another sentence that shares its ideas.
A fragment lacks either a subject or a verb, for example:
The little girls in dresses at the end of the hallway.
Everything in this fragment just describes the subject. To fix this fragment, a verb would need to be added.
The little girls at the end of the hallway stood and stared for what seemed like forever.
A fragment without a subject could look like this:
Driving around, listening only to music until the sun went down.
This fragment is mostly actions (driving, listening), but without a subject, it doesn’t really make sense. An alternative for this idea could be:
Driving around, he only listened to music until the sun went down.
A pronoun and subtle rearranging makes the difference. Finishing off the idea completes the fragment.
To figure out of your sentence is a fragment, look it without context. Does is make sense without any help from the information in other sentences? It probably makes sense, but can it be a story. Fragments usually surface when a writer is trying to expand on something said previously. Leaving off a subject just because you’ve already mentioned and not using a pronoun can do that.
The thing about most grammar conventions is when they’re overlooked, the writing can improve stylistically. Fragments are often used by writers in publications as emphasis to reinforce important information and ideas.
“’Classic.’ A book which people praise and don’t read.” Mark Twain, a renowned American author, using a fragment to emphasize the main idea he tried to convey.
If used properly, fragments can be powerful tools to affect an audience on a different level. If not, well it kind gives the impression of chaotic incoherence if noticeable enough.