Amazon is breaking into physical retail in a new way.

Amazon's checkout-free grocery store opens in Seattle on Monday.

The online retail giant first started testing its grocery store with employees in December 2016, when it also revealed its vision for a store without cashiers.

The store, called Amazon Go, doesn't work like a typical Walmart or supermarket — instead, it's designed so that shoppers will use an app, also called Amazon Go, to automatically add the products they plan to buy to a digital shopping cart; they can then walk out of the building without waiting in a checkout line.

The store opening Monday is 1,800 square feet, according to Reuters, and it's located in an Amazon office building.

The idea is that Amazon's machine-learning technology can automatically identify when a product is added to your cart, so you don't have to do it yourself. When you leave the store, Amazon automatically charges your Amazon account.

The stores will sell ready-made food, staples like bread and milk, and other grocery products. At 1,800 square feet, the store is relatively small compared with big supermarkets.

Internal company plans show Amazon could build 2,000 grocery stores across the US in the next decade, Business Insider previously reported.

Here is what Amazon says it will be like to shop in one: