The past participle is a verb form used with have, has, or had to make perfect tenses and with be to make passive forms. In regular verbs, the past participle usually ends in -ed. In irregular verbs, the past participle has special forms that must be learned as vocabulary.

Regular past participles are formed by adding -ed to the base form of the verb. For verbs ending in e, add only -d. For verbs ending in a consonant plus y, change y to i and add -ed. For some short verbs with consonant-vowel-consonant, double the final consonant before adding -ed.

Rule
Add -ed to the base form to make the past participle of regular verbs.
Add -d to verbs ending in e to form the past participle.
Change y to i and add -ed for verbs ending in a consonant plus y.
Double the final consonant and add -ed for short verbs with consonant-vowel-consonant.

Irregular past participles do not follow a single rule and must be memorized with their base forms. Many common verbs have irregular past participles that are different from both the base form and the simple past. Some irregular verbs have the same form for the simple past and past participle, but their use in sentences still follows the same grammar.

Word/Phrase	Definition
gone	The past participle of go is gone.
done	The past participle of do is done.
seen	The past participle of see is seen.
made	The past participle of make is made.
had	The past participle of have is had.
been	The past participle of be is been.

Perfect tenses use have, has, or had plus the past participle to show that an action is completed relative to a time. The present perfect uses have or has plus the past participle. The past perfect uses had plus the past participle. The past participle does not change for person or number; the auxiliary verb does.

Rule
Use have or has plus the past participle to form the present perfect.
Use had plus the past participle to form the past perfect.
Keep the past participle unchanged and select the correct auxiliary.

The passive voice uses be plus the past participle to focus on the receiver of the action. The form of be changes for tense and subject, but the past participle stays the same. In the passive, the agent can be added with by, but the main structure is be plus past participle.

Rule
Use be plus the past participle to form the passive voice.
Change be for tense and subject, not the past participle.
Add by plus a noun to show the agent if needed.

Regular -ed past participles have three common pronunciations in English. The ending is pronounced as t after voiceless sounds, as d after voiced sounds and vowels, and as ɪd after t or d sounds. Irregular past participles have individual pronunciations that should be learned with the word.

Word	Notation	Description
walked	t	The -ed ending is pronounced as t after a voiceless sound.
called	d	The -ed ending is pronounced as d after a voiced sound or a vowel.
wanted	ɪd	The -ed ending is pronounced as ɪd after t or d.

The past participle is formed with -ed for regular verbs and with special forms for irregular verbs. It is used with have, has, or had for perfect tenses and with be for the passive voice. The main challenges are spelling rules for regular verbs, memorizing irregular forms, and pronouncing -ed endings correctly.