What Are Zero Confirmation (0-Conf) Transactions?

A Zero Confirmation Transaction (0-Conf) is a Bitcoin transaction that has been broadcast to the network but hasn't yet been included in a block. It is essentially an unconfirmed transaction. When a user initiates a Bitcoin transaction, it's first relayed to nodes within the network. Before the transaction gets verified and added to a block by miners, it remains in this unconfirmed state. This state poses risks as the blockchain hasn't secured the transaction, making it susceptible to double-spending attacks. For speedy transactions, such as vending machine purchases or Bitcoin ATM withdrawals, users might accept 0-Conf transactions. However, exercising caution and ensuring transactions are fully confirmed is crucial to guarantee security and avoid potential double-spending.