There's a lot at stake for both sides. Amazon has built a following, but wants to grow its business globally. Meanwhile, brick-and-mortar retailers struggle to keep shoppers from using their stores as showrooms to test out and try on items before buying them for less on Amazon.
The holiday season ups the ante. Both online and brick-and-mortar retailers can make up to 40 percent of their annual revenue in November and December. And this year, they're competing for the growing number of shoppers who are as comfortable buying online as in stores.
Holiday sales are expected to rise 3.9 percent to $602.1 billion, according to The National Retail Federation. Of that, about $78.7 billion is expected to be online, up 15 percent from last year, according to Forrester Research.
Here's how the fight is playing out:
One of Amazon's biggest advantages is its low prices. It can charge less for everything from TVs to T-shirts because it doesn't have the high costs of running physical locations.