Online shopping’s convenience can be tripped up by long shipping times, keeping retailers like Amazon from being the go-to place to pick up ice cream or deodorant.

That’s why the online retail giant is experimenting with same-day delivery in a few cities, says Marcus Wohlsen, senior staff writer at Wired. These new trucks would come pre-loaded with items just waiting to be ordered.

“You’ve got this fleet of trucks that’s constantly combing through city neighbords,” Wohlsen says. “Lo and behold, somebody orders something that Amazon predicted they or someone in that general vicinity would order and it’s already on that truck ready to bring to that person’s door.”

Amazon’s recent interest in drone delivery has also attracted attention recently. Though those trucks “aren’t nearly as sexy as a drone,” Wohlsen says, they’re much more efficent, and give Amazon control over more of the buying process. But filling those trucks and sending them out presents a big logistical problem.

“You can’t virtualize that tube of toothpaste; you still have to figure out how to get it there,” Wohlsen says. “That said, I think that companies like Amazon and Google are in the best position to make advances in the field of logistics because logistics is a very, very complicated math problem. That’s what these companies prioritize. It’s how they make money.”

For Amazon, Wohlsen says, the move is all about trying to “overtake brick and mortar stores as the main way people buy things. Online retail is still a very small portion of commerce in the U.S. It’s something like 6 percent of retail purchases. There’s a lot of runway left for Amazon.”