The 2025 Identity Landscape series: Combining Graphs and Alternative IDs for Maximum Connectivity

Identity Resolution at Scale: Combining Graphs and Alternative IDs for Maximum Connectivity

Digital advertising is powered by connections. Every time a brand serves an ad, measures a campaign, or controls how often a user sees a message, it relies on linking together signals that reveal who that user is. Forrester’s Q4 2024 Identity Resolution Survey found that 70% of marketers struggle to identify and reach audiences across multiple touchpoints, making connected customer experiences increasingly difficult to achieve.

Without these connections, the digital ecosystem quickly becomes fragmented: the same user looks like ten different people across devices, channels, and platforms, making effective advertising almost impossible.

This is where the concept of alternative IDs and identity graphs comes in. When combined properly, they unlock the ability to recognize audiences at scale, measure campaign effectiveness, and create consistent experiences across devices.

What is an alternative ID?

Alternative IDs were developed to provide a stable way of recognizing and connecting audiences across the digital ecosystem. They overcome the limitations of signals such as third-party cookies, which are siloed and specific to certain channels.

Alternative IDs can be built in different ways, using deterministic signals, probabilistic methods or a combination of both. They may also incorporate various privacy-preserving mechanisms depending on their design and the regulatory environment where they operate. Regardless of how they are constructed, their primary role is to make unaddressable audiences addressable, helping advertisers reach users that would otherwise be invisible, and to provide a consistent way to target, optimize and measure campaigns across environments.

While alternative IDs are key for identity resolution, combining these with an identity graph provides a complete view of users' digital footprint by resolving identity at the device, individual, and household levels.

What is an identity graph?

An identity graph is essentially a map of relationships between identifiers. Think of it as a living database that records how different signals relate to one another:

A login email may connect to a browser on a laptop
A mobile advertising ID may connect to an app user
An IP address may connect multiple devices used within the same home

The graph doesn’t just store data; it creates connections. By linking these identifiers, it allows advertisers, publishers, and platforms to understand that seemingly different signals actually represent the same user or household.

Without this connective layer, every interaction would remain siloed. An ad shown on a smartphone wouldn’t “know” that it reached the same person who just saw an ad on CTV. Frequency capping, sequencing, and attribution would all break down.

Graphing provides a range of benefits for anyone involved in digital media. By connecting identifiers, a graph expands scale, increasing the number of users who can be recognized and addressed. It also improves accuracy by reducing duplication and ensuring measurement reflects real reach and frequency.

In short, graphing makes advertising more efficient and effective. Campaigns reach the right people, budgets go further, and users experience fewer irrelevant or repetitive ads.

Combining graphs and alternative IDs for identity resolution

Individually, IDs and graphs enhance identity strategies, but together they create a more complete, complementary solution. Alternative IDs bring addressability into environments where legacy identifiers fall short by helping bring previously unreachable users into view. Their limitation is that they rely on widespread adoption across media properties and channels. Identity graphs complement this by connecting signals around these IDs and bridging gaps where adoption is limited. Used together, they provide a comprehensive view of audiences, supporting consistent targeting, optimization and measurement across channels.

At ID5, our solutions are built on the combined strength of our identity graph and our alternative ID and are designed to address the challenges of scale and compliance. What makes our approach particularly effective is that the ID5 ID is the most widely adopted alternative ID in the industry, thanks to its ability to deliver scale by processing a variety of signals to reconcile identity.

Both our graph and ID are built on consented signals, ensuring compliance with the strictest data protection regulations, such as GDPR. This privacy-focused foundation is why ID5 is one of the few graph providers able to operate effectively in Europe and why our adoption is so widespread.

Looking ahead, the combination of alternative IDs and identity graphs will only grow in importance as channels like CTV, digital audio, gaming, and retail media take a bigger role in the advertising mix. These environments are often siloed, making the interplay between IDs and graphs essential to reaching audiences responsibly and effectively at scale. We’ll dive deeper into identity within these channels in upcoming articles in our Identity Landscape Blog Series.

The 2025 Identity Landscape Series: Adaptive Identity