A past participle is a nonfinite verb form that can be used as an adjective, to form perfect verb tenses, and to form the passive voice. It is one of two types of participles, along with present participles. The past participle is used to describe an action that was started and completed in the past. In English, the past participle of regular verbs is usually formed by adding the suffix "-ed" (e.g., "learn" becomes "learned"), while the past participles of irregular verbs have numerous endings like "-en," "-n," "-ne," and "-t" (e.g., "kneel" becomes "knelt") .

The past participle is used in several tenses, especially perfect forms, such as the present perfect, past perfect, future perfect, and third conditional. It is also used in the passive voice, where the subject of the sentence acts as a receiver of an action rather than a performer.

In addition, past participles can be used (by themselves or as part of participial phrases) as adjectives to modify a noun or pronoun. Participial phrases are phrases headed by a participle that modify a noun or pronoun in the main clause of a sentence.

To avoid a dangling participle when using a participial phrase at the start of a sentence, place the noun phrase being modified immediately after the participial phrase.