Attention Walmart Shoppers: You may soon be hit with a slew of ads while shopping

• Walmart is expanding its in-store advertising, as first reported by CNBC. 
• The retail giant will be promoting ads through its store radios and demos.
• One analyst said that we may be at an "inflection point" for in-store advertising opportunities.

Soon, you may notice something different about your local Walmart. Over the speakers, you might hear a promotion for a product at a discount. Or you could find yourself in front of a sample table with the latest product to try.

Walmart is expanding how brands can advertise their products to customers, as are other companies with large physical presences, like Target and Kroger. While there's been a big focus on online advertisements over the past few years, many retailers are beginning to lean into their brick-and-mortar locations as new potential platforms to bring in advertisement revenue from brands that want their products to get more attention.

A return to old-school advertising with a digital twist

Insider Intelligence analyst Andrew Lipsman describes the trend as "a digital take on analog media." 

"It is, in a sense, going back to some of the traditional hallmarks of marketing and advertising," he said. Insider Intelligence is a sister company of Insider.

But in-store retail media, the term used to describe how stores can make space for advertising in their physical locations, looks differently than the truly old-school methods used decades ago. Instead of cardboard cutouts at the end of aisles or big blown-up signs promoting sale items, in-store promotions today can look more digital and dynamic. 

Walmart, for instance, has pursued more digital-forward ways to advertise in stores for years now. The company already promotes third-party advertisements on digital screens, TVs, and self-checkout registers. Now, it's testing in-person demos in a beta test across a handful of stores, as first reported by CNBC. 

Walmart declined to comment on its retail media expansion, citing its quiet period before earnings, but directed Insider to a June press release that said that it's planning on expanding its in-store demos from 120 stores to 1,000 by the end of the year. 

The company will also be offering ad spots on its radio station, Walmart Radio, for the first time, which advertisers can use to promote products by region or store. 

Retailers can use their physical footprints as an advantage to promote advertisements

Most retailers — like Target, Walgreens, and Costco — have a much bigger footprint in the physical world than they do online. According to Lipsman, retailers' in-store audiences are on average 84% bigger than their digital audience. Walmart, for instance, has around 200 million shoppers every month that it can reach with brand messages.

And that's good news for advertisers, who typically want to reach audiences at scale. In-store ads also offer advertisers an opportunity to target customers when they're in the right mood, meaning they're already inside a store and ready to spend money.

A March report from Insider Intelligence said that the retail media market is worth an estimated $40 billion today. Though in-store advertising "remains a nascent market segment," shoppers should be "thought of as 'eyeballs' for brands to reach," the report said.

"We're at the beginning of an inflection point where this opportunity starts to really accelerate," Lipsman said.