Food delivery has exploded in popularity since the start of the pandemic, serving as a lifeline for restaurants that usually rely on people dining in. But for many eateries, the amount of delivery requests they are getting is more than they can actually handle within their restaurant kitchens, which means they have to rely on ghost kitchens to help delivery orders stay afloat.

So, you might be asking: What’s a ghost kitchen? Also known as a “virtual kitchen” or “cloud kitchen,” these facilities are separate from restaurants but have all the things a typical restaurant would have such as stoves and walk-in refrigerators. They are dedicated solely to making and delivering to-go orders for outside restaurants, and oftentimes, the chefs cooking in them don’t even work for the restaurant whose recipes they’re preparing. But if the ghost kitchen does its job right, the customer never knows their food wasn’t prepared in the back of the house at their favorite restaurant.

Ghost kitchens first became a “thing” in response to the rise of online food delivery services, like DoorDash and Grubhub, which gave people the ability to get delivery from many restaurants that previously only offered dine-in or take-out. Those restaurants still needed to cook meals for their in-house customers, so some would rent time in a ghost kitchen — which can be as large as a warehouse — to meet the extra delivery demand. Some restaurants even choose to completely outsource their online delivery. The company Reef Technologies, for example, operates more than 4,500 ghost kitchens that can handle the entire process for a restaurant.

“It doesn’t cost them anything,” COO Carl Segal told the New York Times in September. “We enter into a partnership with them, we keep the revenue and pay them a royalty percentage every month.”

While these ghost kitchens are certainly helping restaurants survive the pandemic, it’s not a flawless model: if a restaurant doesn’t ensure that the quality of the food coming out of a ghost kitchen meets its standards, the brand can take a hit. However, there have been some rather unexpected benefits to come out of the ghost kitchen model.

For instance, a restaurant in San Francisco called Dosa only serves food out of ghost kitchens now as a way of avoiding the overhead costs of operating a physical location — where most of the space is given over to an empty dining room, and most of the rent going for a prime location that no longer matters.

Others are using ghost kitchens to generate more vital delivery income by expanding their delivery market — Manhattan restaurant Jack’s Wife Freda, for example, will soon use Reef Technologies’ ghost kitchens to deliver food to customers in Brooklyn.

All in all, ghost kitchens are yet another example of how new opportunities can arise from crisis situations. And while we all hope to be dining in at our favorite eateries again soon, we can reasonably expect ghost kitchens are here to stay.