what is a past  participle ? explain with a example

Past participles are used for all perfect tense forms of a verb and in the passive voice in English. It shows something that started in the past, but continues until now. For regular verbs, we normally add ED to form past participles. However there are many verb forms which change in a different way. It is just a matter of a lot of practice and hardwork in order to come to terms with these exceptional verb forms.

sing, sang, sung 
drink, drank, drunk 
do, did, done 
go, went, gone 
make, made, made 
find, found, found