Google is pushing their new payment app based on NFC (Near Field Communication), which can essentially turn your smart phone to virtual a credit card!
NFC or Near field communication, provides the facility for simplified transactions, data exchange, and wireless connections between two devices in close proximity to each other, usually by no more than a few centimeters. So while taping your NFC enabled mobile on a NFC enabled payment point you can transfer the required credit for making purchases.
Once you tap your smart phone having Google wallet, you need to authorize the transaction by entering your PIN. Get your Google Wallet.