When do we use itrader? Can it be used in selling/buying something here on DP? Or giving ebook reviews? Or in providing service? Can someone ask for itrader instead of money in a certain service that is provided?
Only if money are involved for buying/selling ... so for getting free books no ... if no money, only for exchanging stuff ...
iTrader is not a kind of currency. It is used to allow people to leave feedback on transactions. If you use eBay, you could compare it to their feedback system.