Wal-Mart (WMT) is test-driving a system that could dramatically change the way Americans shop. The program, called Scan & Go, lets customers scan their own goods with their smartphones, pass through a self-checkout line and zip out of the store.

The company recently conducted a trial run with employees and their friends and families at a Wal-Mart Supercenter in Rogers, Ark., not far from the retail giant's Bentonville headquarters. If all goes well, the nation's largest retailer could begin rolling out Scan & Go nationwide. Is this the future of shopping? 

Here's a brief guide:

How does the system work?

First, shoppers install the Scan & Go app on their iPhones. Then, while cruising Wal-Mart's aisles, they scan the bar codes of the items they want and bag them as they shop. Once they've got everything they need, the app sends data on the scanned items to a self-checkout station. The customers stop by the payment station, swipe a credit card, and -- voila -- they're on their way. The test version doesn't allow customers to pay using their phones, which would let them skip the payment station, but mobile payment could be coming.

What's the point?

Wal-Mart figures the new system will pay off for customers and the company alike. A trip to the big box theoretically becomes more enjoyable for shoppers if they can avoid long checkout lines. Meanwhile, the company says it can save $12 million on cashier salaries for every second it can shave off the typical checkout process.

Has anyone tried this before?

Yes. This is the fourth technology that large-scale retailers have seized on in their ongoing quest to simultaneously cut costs and make shopping easiet, Paul Weitzel, a managing partner at the retail consulting firm Willard Bishop, tells Reuters. Supermarket chain Jewel-Osco, for example, experimented several years ago with giving customers handheld scanners. "With smartphones and improved technology," Bishop says, "we're only going to see more of this."

Will this really change the way we shop?

Existing self-checkout lines become annoying when the scanning contraption doesn't recognize an item and you have to wait "for a Wal-Mart worker to intervene," says Christina DesMarais at PC World. If Scan & Go eliminates such snafus, it's a blessing, but it won't be revolutionary until you can pay with the app and avoid the checkout counter altogether. This "fledgling program" is just the beginning, says Jennifer Van Grove at VentureBeat. Wal-Mart Labs, the retail giant's social and mobile product incubator, has been snapping up app makers and mobile payment startups, all in an effort to zip customers out the door faster. And not a moment too soon, says Jose Martinez at Complex. Those of us who love Wal-Mart's low prices hate its long checkout lines. If the company can save money and lose the bottleneck at the same time, it's "a match made in heaven."

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