Participles are verb forms that can function as adjectives, noun modifiers, or parts of compound verbs. There are two types of participles in English: present participles (ending in -ing) and past participles (usually ending in -ed, -en, or -t). For example, in the sentence "The running water was cold," "running" is a present participle used as an adjective. In the sentence "The broken vase was on the floor," "broken" is a past participle used as an adjective.