On December 1 the RBI launched a pilot version of the e-Rupee in four cities. Since it's issued by the RBI, it's called a central bank digital currency or CBDC. But we already make digital payments via UPI-based apps like Google Pay, PhonePe and Paytm. So how are CBDCs different and what's the incentive for people to transact in e-Rupees? Moreover, e-Rupees have to contend with cash. The blockchain makes every transaction traceable. So can India's CBDC beat UPI? Can it beat the anonymity that cash offers? Here is a look at what it will take for CBDCs to become a widespread