Google Wallet's single-biggest problem to date in the US has inarguably been carriers. US carriers (except Sprint) wouldn't allow Google the necessary control of the "secure element" in order to make NFC payments, and as such, Google Wallet consumer adoption has essentially been trivial. With Android 4.4, that finally changes.

The new version of Android completely eschews the secure element paradigm and has instead opted for a virtual solution, using what Google calls "Host Card Emulation" technology to get the job done.

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