A participle is a verb that ends in:

A participle is a verb that ends in -ing (present participle) or -ed, -d, -t, -en, -n (past participle). Participles may function as adjectives, describing or modifying nouns.

The dancing parrots entertained the crowd.

The wrecked sailboat washed up on shore.

But participles have another function. When used with helping verbs such as to be and to have, they are action verbs and form several verb tenses.

She is thinking of the children.

The conference room had been cleaned before they arrived.