First some clarifications. While the majority of central bank issued currencies (fiat currencies) in existence around the world are already in digital form, a fiat currency held in digital form is not the same as a Central Bank Digital Currency (CBDC).
What is a CBDC?
A CBDC generally refers to electronic or virtual central bank (fiat) money that is created in the form of digital tokens or account balances which are digital claims on the central bank. CBDCs will be issued by central banks and will be legal tender.
Many CBDCs that are being researched and developed employ Distributed Ledger Technology (DLT), with the recording of transactions on a blockchain.