A participle is a word that functions like an adjective and also shows verb features like tense and voice. Participles are modifiers, so they must have a noun to modify. A dangling participle is one that has been left out in the cold with no noun to modify.
For example:
While strolling through the kitchen, the smoke alarm went off.
Was the smoke alarm taking a stroll?
How can we fix this sentence?
While I was strolling through the kitchen, the smoke alarm went off.