What Is Identity Resolution? How It Works
Are your digital ads underperforming because you can’t connect fragmented user data into a single profile? You’re not alone. Identity resolution is one of the most crucial yet misunderstood strategies in programmatic advertising. This guide explains what identity resolution is, how it works, and why it’s transforming digital marketing.
Whether your goal is to increase CTRs, lower CPAs, or simply make smarter ad spend decisions, this blog will show you how identity resolution unifies customer profiles across devices and channels, powers targeting, improves audience segmentation, and delivers personalization and measurable ROI at scale.
Identity resolution is the process of linking user data across devices, platforms, and touchpoints to create a unified customer profile. It consolidates fragmented identifiers like cookies, device IDs, and email addresses into a single, persistent identity. This enables advertisers to understand who their customers really are, regardless of how or where they engage.
For advertisers, identity resolution is critical because it powers precise targeting, accurate attribution, and personalization at scale. In an era where third-party cookies are vanishing, it’s becoming the foundation of effective digital marketing.
There are two main approaches to identity resolution: deterministic and probabilistic.
Both methods complement each other. Deterministic ensures precision, while probabilistic expands reach and fills in the gaps where deterministic data isn’t available.
In practice, most identity resolution strategies combine the two approaches. For example, a retailer might use deterministic login data when customers sign in but then use probabilistic models to connect browsing behavior when they’re logged out. This hybrid approach ensures scale without sacrificing accuracy.
An identity graph is a specialized database that stores and connects all user identifiers across channels. Think of it as the “map” that powers identity resolution.
It links device IDs, cookies, hashed emails, and other identifiers into a single profile. Identity graphs are constantly updated in real-time to reflect changes in user behavior, giving advertisers a dynamic, 360-degree view of their customers.
Identity graphs are particularly important in the cookieless era. As cookies disappear, advertisers rely on identity graphs built with first-party data and privacy-compliant identifiers to maintain visibility across the customer journey.
In programmatic advertising, identity graphs allow for more accurate targeting, suppression of irrelevant audiences, and improved customer journey mapping. Without an identity graph, advertisers risk wasting impressions on duplicate or irrelevant audiences.
Identity resolution typically works through several steps in a programmatic environment:
This process ensures that the right message reaches the right person at the right time.
An advertiser running a cross-device campaign, for instance, could use identity resolution to recognize that the same person who viewed an ad on mobile later converted on desktop. Without this connection, attribution would be inaccurate, and future optimization efforts would be flawed.
Identity resolution unlocks powerful advantages for advertisers:
Beyond these, identity resolution also enables:
Despite its benefits, identity resolution comes with challenges:
Additionally, consumer trust is critical. Mishandling data or failing to honor consent preferences can damage brand reputation. Advertisers must implement robust data governance and privacy-first strategies to overcome these challenges.
Identity resolution isn’t just a behind-the-scenes tactic, it drives tangible outcomes for advertisers:
These use cases highlight how identity resolution transforms fragmented data into actionable insights.
Identity resolution underpins precision targeting in an increasingly cookieless world. For one example of this in action, AdExchanger highlights how Blockgraph OnDemand, a data onboarding platform built for small and local businesses, empowers advertisers to match first-party data with premium TV ad inventories, all while preserving privacy. Features like geo-based audiences and collaborative insights reflect how identity resolution enables hyper-specific, household-level targeting across digital and linear channels.
Identity resolution is more than just a buzzword, it’s the backbone of effective digital advertising in 2025 and beyond.
By unifying customer data across touchpoints, advertisers can unlock personalization, improve measurement, and maximize ROI.
We don’t just provide technology, we provide partnership. Our experts help design, execute, and continuously optimize campaigns to deliver measurable outcomes. Whether you’re building brand awareness, driving e-commerce sales, or launching omnichannel campaigns, we bring together the data, creative, and delivery needed to succeed.
Don’t let fragmented data limit your advertising potential. Harness the power of identity resolution and elevate your programmatic strategy today.
BONUS READ: What Is a Device ID? How Device ID Profiles Are Used in Ads