Google AdX (previously known as DoubleClick Ad Exchange) is an ad exchange network. This means it is a programmatic advertising platform, offering real-time bidding (RTB) on ad spaces to ad networks, including AdSense, agencies and demand-side platforms.
Publishers working with Google AdX have access to a larger inventory and can access buyers from Google Ads and other marketplaces using this exchange.
It also provides much more control to publishers over their ad space and allows them to sell their ad inventory directly. There’s also higher competition for ad inventory, which results in increased revenue per ad unit sold.