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Master customer understanding: How identity resolution transforms marketingEstimated reading time: 10 minutes
Blog

Master customer understanding: How identity resolution transforms marketing

By: Epsilon Marketing | September 26, 2025
a woman with icons around her

Identity resolution might sound overly technical or tedious, but it's foundational to marketing today. In today's digital-first environment, recognizing and reaching customers across channels and devices is incredibly complex. Being able to actually speak to people like you know them (because you do) starts with getting identity resolution right, which is no small task. It starts with cleaning up your own customer data—in fact, it might be one of the most critical ongoing processes in your marketing engine. 

Keep reading to learn more about how identity resolution can power your marketing strategy.

Identity resolution: the foundation for deep customer understanding

Identity resolution is key for marketers looking to bolster their campaigns. It allows brands to know their customers more deeply because they can see beyond their limited view of them. As brands move away from using third-party cookies, identity resolution has emerged as a powerful means to connect with consumers.

That’s because it organizes a brand’s first-party data to align and enrich it. A solid first-party data strategy is centered around identity resolution, and when used in martech tools like customer data platforms (CDPs), clean rooms or engagement platforms, marketers can build higher-performing campaigns that reach the right people.

Unifying customer data for a holistic view

Consumer data is inherently fragmented. When brands use identity resolution inside their martech and adtech, they can see what their customers are doing in the wild and use that data to fill in data gaps. Once those gaps are filled, brands can build more holistic profiles and use those insights to build a better audience.

Identity resolution helps unify data by assigning individuals a unique, privacy-complaint identifier. These identifiers are accurate, constantly optimized and can connect disparate data points, giving brands a single view of each consumer.

This is important because consumers have, on average, more than five identifiers attached to them, such as emails, device IDs and cookies. Identity resolution helps brands identify customers in their existing file that they may be counting more than once, and connect disparate behaviors to a single profile. For instance, a brand might “count” a person twice because one profile is attached to their email while the other is attached to their device ID.

The power of "seeing customers better"

When a brand has more holistic customer profiles, they can create stronger marketing strategies for all their customers, including prospects. That's why identity resolution is critical in martech like CDPs.

For the customers they already know, they can develop more personalized marketing that speaks to an individual's interests on the channels and devices they prefer.

They can also identify customers who are loyal to their brand that they don’t have first-party data on. These are shoppers or customers who perhaps frequently buy but, for a variety of reasons (buying with cash, for example), haven’t attached their purchases to their name or device.

Brands can also identify potential reasons customers are dropping off. Customers abandon brands for a variety of reasons. When data gaps are filled, it often puts pieces into a puzzle. Did they leave because they moved out of the market? Have they been buying a competitor?

Speaking of dropping off, brands can now target disengaged customers because they have a fuller picture of what motivates them, including which devices they prefer. And they can win over competitors' customers by using third-party data to see whether customers are shopping with competitors. This helps marketers try to win them back.

And lastly, new customers are also easier to find. A more accurate view of their customers gives brands an important window into who buys from them now, and they can use those insights to find new customers who look just like them.

Driving precision and efficiency in digital media and advertising

Minimizing ad waste and maximizing reach

Holistic customer profiles narrow down which customers are most likely to engage with a brand, and that person-based identity solution gives brands the power to measure at an individual level. Knowing what works (and what doesn’t) reduces a brand’s media waste. And when something doesn't work, they can pivot faster because of granular attribution.

But it also opens up a brand's universe of buyers. Marketers can marry online and offline identities, including transaction data or identifiers like email, back to a pseudonymized ID and gain even more insights into a customer’s preferences and behaviors. This maximized reach is what allows brands to reach their customers—including those who've fallen off for whatever reason—and attract new customers who look like their best ones.

Overcoming walled gardens

This measurement capability extends to spaces like walled gardens. Walled gardens in the marketing ecosystem are extremely common and employed by tech giants like Google, Meta and Amazon. Brands using walled gardens to run ad campaigns often get limited view into their results and aren't given granular measurement on the people and audiences their ads reached.

Measurement is difficult within walled gardens because of the disparate nature of reporting and identity across environments. Each walled garden differs in what measurement it offers, meaning metrics can vary across each platform and can be hard to compare. And it's extremely hard to track and understand users across these platforms.

Technology like a data clean room that has identity resolution built in can provide multi-touch, multi-attribution at scale across channels and platforms, including walled gardens.

Enhancing retail media performance

Identity resolution also bolstered retail media performance. Retail media thrives when it enables retailers to connect brands with real shoppers in ways others can't. Person-level identity gives brands and retailers to connect those audiences and measure the success of campaigns delivered to them.

Strong identity allows retailers to locate hand-raisers—shoppers actively in-market for a product or category—across all channels. Whether they’re researching online, browsing in-store or streaming content on connected TV, person-level identity enables retailers to meet shoppers with relevant messaging at the right moment.

Elevating customer experience and cross-channel engagement

Delivering harmonized experiences

With persistent identity, brands can see a customer’s path to purchase from interest to actual conversion. These deeper view into the customer journey helps coordinate experiences across channels so they feel harmonized and seamless. Dynamic identity resolution coupled with machine learning and AI can examine a customer's historic signals and use them to predict what they might need next.

Most importantly, identity resolution acts as an anchor to a customer's true experience. Consumers react, and when a brand can see those reactions (both positive and negative), it can make adjustments in how it talks to and engages to boost customer experience. It's important to use data to learn and tailor a customer's behaviors and preferences to build an experience that fits them.

Rich customer profiles can also help predict what a customer might do and what they have done historically. Brands can step in when strange activity happens and help mitigate risk.

Enabling true personalization

When brands know their customers better, they understand what they like. Advertising and marketing can get more personal, delivering messages that matter to real in-market people on the devices they prefer.

Customers expect nothing less than personal, purposeful brand experiences with every interaction. According to Epsilon research, 76% of respondents said they view brands negatively when they include inaccurate information about them in their marketing. And more than half said they want to receive personalized marketing from brands.

Personalization should be integrated into the entire customer experience, from first visit to becoming a loyalty member and beyond.

Leveraging first-party data and privacy-safe solutions

Building a strong first-party data strategy

So where does a brand start? To deploy identity resolution, they first need data to clean. They need to consider how they're collecting data, what tools they're using to organize said data and how identity resolution is incorporated into those systems.

But brands need a comprehensive, thoughtful data strategy that goes beyond merely collecting data. To understand their best and next best customers, marketers need a holistic understanding of who each person is, not just how they engage with them. A complete data strategy, powered by the right technology and identity resolution, uses first-party data, enhanced by zero-, second- and third-party data to drive better customer experiences and higher performing campaigns.

A solid first-party data strategy also sets the stage for a stronger AI implementation strategy. Accurate, unified data creates a solid platform for tools like  to use. And with real-time insights on customers, it enables AI use on an individual level and at scale.

Securely expanding audiences with clean rooms

A data clean room is a secure environment where data from various sources—including walled gardens, partner data, regulated data, and much more—can come together in a privacy-safe way. While many expect these martech tools to be empty boxes used for collaboration with partners, the right data clean room can help you better understand your current customers and find new ones. The secret to success is using a clean room with data and identity pre-loaded.

Clean rooms pre-equipped with these features give brands a richer view of customers and prospects. They take a brand's customer data and augment it with the data already built in, making existing customer profiles more comprehensive and identifying potential buyers based on those insights.

Fostering long-term customer loyalty and retention

Nurturing customer relationships

Unsurprisingly, when a person feels like they’re being heard, they have a higher affinity for a brand. Emotional loyalty starts with continued positive customer experiences.

Customer identity management is foundational to modern marketing. It helps brands understand who an individual customer is across multiple channels (and devices) to better target and optimize marketing efforts, including digital advertising. When marketers attribute customer behavior and interactions accurately, they can build better customer relationships.

A huge tool that often goes overlooked are loyalty programs. These data-rich environments are full of customer insights, and when used effectively, can bolster a brand's first-party data and impact their overall business success.

Measuring true ROI and driving business growth

Proving marketing effectiveness

Measurement is the bread and butter of a marketing campaign. When fueled by strong data and identity, and activated through a single source of truth, brands can rest assured that their measurement is accurate and granular. When using martech and adtech in conjunction with things like AI and machine learning, you're enabling your data to continue to get better.

Holistic solutions are built for this type of feedback loop. As campaigns progress, marketers get feedback on success and can apply insights back to their data and adjust the strategy in the future.

At Epsilon, identity resolution is built into our suite of solutions. Epsilon's COREid is the industry's most accurate, stable, and scalable identity resolution solution. It delivers person-first marketing that resonates with shoppers across their channels and devices, giving brands peace of mind that they're reaching the right people with messages that matter.

Connect with Epsilon: See how identity resolution changes marketing.

IdentityCustomer InsightsDigital MediaDataPersonalization
Insights

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