Tutoring English, this topic is a classic. The tutor recalls hearing it decades ago….

A modifier gives more meaning to its sentence, but isn’t the main idea. Some examples (with modifiers in italics):

Sitting around the campfire, we noticed a UFO.

We drank our coffee in silence, waiting for the executives to arrive.

A dangling modifier is one whose reference is vague. Consider the sentence

Lurking among the trees, the zombies appeared.

Who is lurking among the trees – the zombies or the viewers? Perhaps

Lurking among the trees, we watched as the zombies appeared.

or else

Watching the trees, we noticed zombies lurking among them.

clarifies the intended meaning.

HTH:)

Source:

Hodges, Horner et al. Harbrace Handbook for Canadians, sixth ed. Scarborough: Nelson Education Ltd., 2003.

Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.