Third-party cookies were designed to anonymously store information under the control of end users, but were seized on by ad tech providers to amass and link datasets to target and measure highly specific ads.
As third-party cookies disappear, ad data and third-party processing will decline in breadth, availability and quality.
Ad targeting, buying and optimization processes will be disrupted and constrained, especially for performance-oriented campaigns and custom audiences. Current ad measurement, attribution and optimization practices will become peripheral or irrelevant as cookie data gaps undermine attribution and optimization, incrementality testing and app-to-web tracking.
Google described the end of third-party cookies as an important step toward greater privacy for web browsers, and it comes on the heels of Apple’s April 2021 iOS update 14.5, which featured a new consent protocol called App Tracking Transparency (ATT). ATT governs and constrains how apps and advertisers can use uniquely identifiable data like device ID to target, measure and optimize campaigns.