Google Wallet — along with Google Offers — is built on an open platform that combines multiple credit cards, loyalty programs and offers at the point of sale. Payment is made by swiping your smartphone at checkout. Essentially, Google is turning your phone into your wallet.
The Google Wallet service must be associated with a Google account to begin using it. After agreeing to terms and conditions and entering a PIN, you can start the process of provisioning your cards to your account.
Right now, Google Wallet only works with Citi-Mastercards and the Google Prepaid Card. Visa and Google announced a worldwide agreement to support the Visa payWave app, but it will still be up to the financial institutions and banks to add support