iOS 10 has a feature that most people aren't aware of: Limit Ad Tracking (LAT). This feature allows people to opt out of having advertisers track their personal information in order to provide targeted advertising. adjust released research this morning on the adoption rate of this technology by users, and their numbers show that so far a total of 18% of users worldwide and 20% in the US have turned on the feature.
Limit Ad Tracking is simple to enable -- users just need to launch System Preferences, tap Privacy, then tap on Advertising (at the bottom of the Privacy screen). Enabling Limit Ad Tracking doesn't mean that you'll get any fewer ads; it's just that information about you won't be sent to the advertisers, meaning that you'll probably get less relevant ads.
For advertisers, this isn't good news that the adoption rate is almost at 1/5 of all users at this point, since they won't be able to explicitly target users who have LAT enabled. By getting the word out about LAT, more people may decide to opt in, as right now it's pretty much a "hidden feature" of iOS 10. This infographic produced by adjust shows some fascinating facts about where the LAT feature is gaining the most traction.