For people to be revived (his friends & family).
But most of the time it is them wishing for Goku to be revived.
Chat with our AI personalities
He was training the the sky temple with Uub and some of his original enemies came to the temple, they somehow made a wish on the dragon balls saying "oh I wish you were young again...then you wouldn't be so tough" and then Boom - Goku became young! That is why Trunks, his grand daughter and Goku are now searching the galaxy for Dragonballs.
Its part three of dragonball where goku turns in to a childand must find these dragonballs
There is no information given in the series about what happened to them prior to the Dragonball Manga/anime. However, the first wish made on the Dragonballs in the series was Oolong who wished for "the panties from a real hot girl".
On earth once but on dragon ball z gt in the black star dragon balls saga you can and will get a rule free wish like bring back a planet with everyone on so you can wish back people more than 1 time like goku wished back krillin with them.
Lets hope that Goku Jr sets out to find all 7 of the DragonBalls. Once he does so, he wishes all of the Z fighters back. And a new series begins!! Forever Alone :(