Amazon may not be touting its efforts in public, but behind the scenes it has been trying to expand its footprint in the ad business, digital media executives say.

To date, Amazon’s ad business has mostly focused on driving online sales with targeted ads on sites across the web, leveraging its rich supply of shopping data culled from years of operating a massive e-commerce business. It can, for example, help an advertiser target people who have recently searched for men’s apparel products.

Externally they have been quiet, but driving sales internally on their own sites is massive. For those brands that sell on the platform, Sponsored Product ads as Amazon labels them are a major component to being successful. Not all brands have organic reach on the platform that provide instant traffic. Ads are just another service Amazon provides in the flywheel that drive further monetization on their platform for 3rd party sellers.