The past participle is one of the non-personal forms of a verb. Its main function is to form the perfect tenses together with the auxiliar verb "haber" (to have, as an auxiliary verb).
1st conjugation -AR: participle ends in -ado
2nd conjugation -ER: participle ends in –ido
3rd conjugation -IR: participle ends in –ido
1st conjugation -AR: participle ends in -ado
2nd conjugation -ER: participle ends in –ido
3rd conjugation -IR: participle ends in –ido