Amazon has thousands of robots filling customer orders this holiday season.
The machines follow barcodes on the floor to find merchandise, then they lift entire shelves and carry them to human employees, who pick and pack the necessary items.
The robots have made employees three times more productive by reducing the amount of time they spend trekking around the giant Amazon warehouses, theWall Street Journal reports.
At some warehouses where the robots are used, employees are expected to scan 300 items a day, up from 100 items daily without the robots, according to the Journal.
Amazon should have close to 10,000 of the robots in its warehousesby the end of this year, up from 1,000 six months ago.
The machines are made by Kiva Systems, a company that Amazon bought for $US775 million in 2012.
Disclosure: Jeff Bezos is an investor in Business Insider through his personal investment company Bezos Expeditions.
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