Il participio passato

The regular past participle is formed with the endings –ato for the 1st, -uto for the 2nd, and –ito for the 3rd conjugation, respectively:

guardato
ricevuto
dormito

The bad news is that there are many verbs with an irregular past participle, like fare/fatto, essere/stato, but the good news is that you can identify some basic groups:

Verbs with past participle in –so (mainly 2nd conjugation):

accendere - acceso
decidere - deciso
prendere - preso
chiudere - chiuso
mettere - messo
scendere - sceso
correre - corso
perdere - perso

Verbs with past participle in –to (both 2nd and 3rd conjugation):

vedere - visto
chiedere - chiesto
rimanere - rimasto
rispondere - risposto
leggere - letto
scrivere - scritto
rompere - rotto
vivere - vissuto
nascere - nato
scegliere - scelto
dire - detto
venire - venuto
morire - morto
aprire - aperto
offrire - offerto

The past participle is one of the most frequently used forms of Italian verbs, because it occurs in all compound tenses, combined with the auxiliary verbs essere or avere.