Should I use a comma with a participle or gerund phrase?

Participle phrases are phrases that modify a noun or pronoun. They add extra context. Here are a couple of examples:

• Example: Walking to the shops, he saw his cousin.
• Example: Upset by his cousin, he went home.
• Example: Frank, hoping to get promoted, applied for the role.
• Example: Anne applied for the role, hoping to get promoted.
• Example: Katy walked home, tired from a hard day in the office.

The two forms of participle phrase you can see here are:

• Present participle (always ending -ing), e.g. walking, hoping.
• Past participles (often ending -ed, but sometimes irregular), e.g. tired, upset.

Note: sometimes participle phrases can be disguised if there is an adverb on the front, e.g. Desperately seeking shelter, he ran into the building.

The comma rules you need to know for participle phrases are:

• For participial phrases before the main clause, put a comma after the participial phrase.
• For participial phrases in the middle of the sentence, the phrase requires commas both before and after it.
• For participial phrases after the main clause, put a comma before the participial phrase.