A “Signal” in Google Ads under the Demographics tab is for optimized targeting, a new feature gradually rolling out to Google Ads Manager users, that may not be available for all accounts.
Google Ads expert Brett Bodofsky pointed it out on Twitter.
Google Ads Liaison Ginny Marvin explained further in a tweet. “It indicates optimized targeting is enabled,” Marvin wrote. “OT uses audiences & demo inputs as signals to find more conversations w/in campaign goals, so you’ll see impressions outside of your set targeting signals. To help distinguish, set signals are labeled as ‘Signals.’”
The Google Ads help page describes optimized targeting as a way to reach customers who have the highest likelihood to convert in a campaign.
Optimized targeting is automatically turned on for all campaigns. It looks at information like keywords on landing pages or in the brand’s creative assets, then finds audiences that can meet the campaign's goals.
Optimized targeting may reduce or stop serving traffic on signals if it finds better-performing traffic elsewhere.
Google suggests that optimized targeting works best to serve to audience segments most likely to convert, acquire new customers beyond existing segments and still meet goals, identify new people who perform well for a specific campaign, and to increase conversions without increasing bids or the cost per customer.