A dangling modifier is a word or phrase that is intended to describe a noun that doesn’t actually appear in the sentence.
Dangling Modifier: Waking up early, the sounds of birds singing could be heard through the thin windows.
Here, the participial phrase waking up early has nothing to logically modify. Participial phrases at the beginning of a sentence usually modify the nearest subject noun in a sentence, but the subject noun in the main clause is sounds, which cannot perform the action of waking up. Fixing this problem requires a bit of rewriting so that the noun the dangling modifier was meant to modify now appears in the sentence.
Revision: Waking up early, I could hear through the thin windows the sounds of birds singing.
It is now clear that the person waking up is the subject I.
Here’s another example
Dangling Modifier: Angry because of the delayed basketball game, many seats were left empty.
In addition to causing fuzziness, the dangling modifier creates an unintended humorous effect. According to the structure of the sentence, the seats were angry, which is something you might see in a cartoon.
The sentence needs to be rewritten so that the dangling modifier has something to logically modify.
Revision: Angry because of the delayed basketball game, fans stormed out of the arena, leaving many seats empty.
Fans are the ones who were angry, so fans now appears as the subject noun in the main clause.
Here’s a couple more examples.
Dangling modifier: After listening to the new release, sales were bound to be high.
Revision: After listening to the new release, Mario knew that sales were bound to be high.
Dangling modifier: Shopping through the mall, the security guard seemed to be following me.
Revision: Shopping through the mall, I thought I was being followed by the security guard.
Dangling modifiers are similar to misplaced modifiers in that they can create confusion, but as you see, simply moving the modifying phrase isn’t enough to add clarity when dealing with a dangling modifier. Most of the time, you need to add or revise words in the main clause of the sentence.
For more practice, check out this video on dangling modifiers by Khan Academy: