A dangler modifier is an error participle a sentence. It occurs when a writer may have wanted to modify the subject but the order of words seems to modify an object instead. An example is in the sentence ' At the age of eight, my family finally bought a dog', ' At the age of eight' is the dangling modifier.
A dangling modifier or participle is when a grammatical modifier is associated with a word or phrase other than the one intended, or with no word at all.
For example, "Walking down Main Street, the trees were beautiful". In this sentence, it sounds like the trees were walking down Main Street, because there is no other subject for it to be associated with.