A participle is a verb form of a word that acts like an adjective.
Words ending in -ing look like verbs, but sometimes -ing words act like an adjective.
The barking dog was very noisy.
The word barking looks like a verb, but it acts like an adjective here because it describes dog.
Sometimes, we put an -ing describing word in front of the noun it describes. We only do this at the beginning of a sentence, and the word right after the-ing describing word must be the noun being described. We put a comma after the participle, before the noun. Here are some examples:
Barking, the dog ran around the room. The participle barking describes the dog.
Running, Jim caught up with us. The participle running describes Jim.
Smiling, Jan opened the door. The participle smiling describes Jan.
A participle ending in -ing looks like a verb but acts as a describing word for a noun. If you begin a sentence with a participle, use a comma after it and put the noun it describes right after the comma.