ID Bridging: The Privacy-First Future of Audience Targeting
ID Bridging is used in digital advertising to link user identifiers across different devices, browsers, and environments. As the use of third-party cookies declines due to browser restrictions and heightened privacy regulations, ID bridging offers a way for publishers to maintain consistent user identification.
By “bridging” identifiers from environments with differing levels of addressability, ID bridging helps sustain the effectiveness of ad campaigns in a cookieless landscape.
In this article, we’ll explore what ID bridging is, how it functions, and why it holds significant value for both publishers and advertisers.
Why does identity resolution matter to publishers?
Identity resolution is the process of recognizing a single user across different touchpoints and interactions, both online and offline. For publishers, this capability is crucial as it enables them to deliver personalized content, maintain high-value audience segments, and maximize ad revenue.
As third-party cookies fade away, publishers need alternative methods to recognize and target users consistently. Effective identity resolution allows publishers to better understand their audiences, optimize user experiences, and offer targeted advertising solutions that appeal to advertisers.
The challenges with traditional identifiers
Traditional identifiers, such as third-party cookies, have long been used to track user behavior across multiple websites for the purposes of ad targeting and personalization. However, these identifiers come with significant challenges.
Firstly, they are increasingly restricted by major web browsers like Safari and Chrome, which block or limit the use of third-party cookies due to privacy concerns.
Secondly, traditional identifiers have limited cross-device capabilities, often failing to recognize users as they switch between devices or apps.
Additionally, third-party cookies face criticism due to privacy concerns and lack of user control, leading to increased regulation. These regulations mandate transparency and consent, further complicating the use of traditional identifiers in digital advertising.
As a result, the industry has turned to more privacy-compliant solutions to adapt to user expectations and legal standards.
What is ID Bridging?
The shift away from third-party cookies has driven the creation and adoption of alternative IDs. An “alternative ID” is any identifier used to track and target users across websites and devices without relying on third-party cookies.
These identifiers vary significantly, depending on the companies behind them and the specific privacy laws of the regions in which they operate.
- Prominent examples of such initiatives include The Trade Desk’s Unified ID 2.0, ID5, and LiveRamp’s RampID.
However, many other solutions continue to emerge. In this context, ID bridging plays a critical role by enhancing the value of bid requests in programmatic advertising. ID bridging emerged as a solution for advertising environments without cookies, such as Safari, where DSPs were not equipped to bid on cookie-less identifiers.
ID bridging allows DSPs to continue receiving cookie-based IDs by linking an identifier from a cookie-friendly browser (like Chrome) to another browser (like Safari) on the same device through attributes such as IP addresses. This bridging helps maintain established connections and bid accuracy in the absence of direct cookies, essentially acting as a cross-browser ID link.
Most ID bridging involves transferring DSP and SSP cookie-based identifiers between different browsers.
How ID Bridging Works?
Publishers use ID bridging to link multiple alternative IDs into a single, enriched bid request through a process known as bid enrichment. By incorporating additional data about users into these bid requests, publishers can increase the likelihood that their inventory will be recognized and considered addressable by ad-buying platforms, ultimately maximizing their ad yield (revenue from ad sales).
To optimize this process, publishers often work with first-party DMPs. This collaboration allows them to implement and test different identifiers, evaluating which provides the best performance and ad yield.
Some legacy data providers have approached bid enrichment by embedding all possible alternative IDs within their tags. While this method increases the range of identifiers, it can introduce limitations, such as slower webpage loading times (latency) and challenges for non-web channels, while also lacking the detailed insights and optimization capabilities that first-party DMPs offer.
Overview of Matching Methods
The combination of deterministic and probabilistic matching methods allows ID bridging to balance precision and scale, providing publishers with flexible solutions to maintain targeting effectiveness even in restrictive environments.
Deterministic approaches prioritize accuracy and consistency, while probabilistic methods offer broader coverage and flexibility, creating a comprehensive strategy for identity management and targeting.
Deterministic Matching
Deterministic matching is the more accurate and reliable method of ID bridging.
This method relies on stable and direct identifiers, such as hashed email addresses or other unique, persistent data points, that remain consistent across multiple devices and environments. When users log in on different browsers or devices, deterministic matching can reliably identify and link them, providing a higher degree of precision and trustworthiness in connecting data.
Probabilistic Matching
Probabilistic matching is broader in scale but less precise. It uses sophisticated algorithms to analyze a combination of signals, such as IP addresses, device types, browser patterns, and other contextual data points.
By interpreting and linking these signals, probabilistic matching can infer connections between different browsing profiles. While it offers the advantage of greater reach and scale, it lacks the absolute certainty of deterministic methods, instead relying on statistical probabilities to make informed guesses about user identities.
Key components of ID bridging
ID bridging connects user identities across various platforms and devices. To do this, it relies on several key components.
First, device IDs. These are unique identifiers assigned to individual devices, such as smartphones or tablets. In mobile environments, these include Apple’s Identifier for Advertisers and Google’s Advertising ID. Advertisers use device IDs to track user behavior within apps. However, with increasing privacy concerns, users now have more control over these identifiers, and some platforms are limiting their use.
Secondly, hashed emails. This means converting email addresses into unique, anonymized strings using cryptographic hashing algorithms. This process allows to match user identities across platforms without exposing personal information.
Third, cross-platform linkage. It’s the ability to recognize and connect a user’s identity across multiple devices and platforms. This is achieved by combining various identifiers to create a unified profile, such as device IDs and hashed emails.
In addition to the primary components, effective ID bridging relies on integrating first-party data directly from a publisher’s or advertiser’s owned assets (e.g., websites, apps, and CRM systems) to strengthen identity resolution while minimizing reliance on third-party data.
Technologies that enable identity unification
Several technologies and tools further facilitate identity unification:
- Identity graphs. These are databases that compile various identifiers associated with individual users, enabling the connection of disparate data points into a cohesive profile. Companies like LiveRamp offer identity resolution services that build and maintain these graphs.
- Customer data platforms (CDPs). CDPs collect and unify customer data from multiple sources, providing a centralized platform for managing user identities. They help in creating comprehensive user profiles that can be used for targeted marketing and personalization.
- Data management platforms (DMPs). DMPs gather and analyze large volumes of data from various sources, including online and offline channels. They assist in segmenting audiences and enhancing targeting strategies by integrating different identifiers.
Benefits of ID Bridging for Publishers and Advertisers
Maintaining ad value
ID bridging helps to keep publisher inventory valuable by preserving addressable audience segments. By linking user identities across different browsers and devices, publishers can offer advertisers consistent targeting capabilities, maintaining the effectiveness of their ad impressions.
Attracting privacy-conscious advertisers
With a growing focus on privacy, ID bridging can make publishers more appealing to top-tier advertisers who prefer privacy-friendly solutions over cookie-based targeting. This alignment with modern data standards builds trust and attracts high-value demand.
ID bridging supports compliance with regulations like GDPR and CCPA. It uses user-consent-based identifiers and transparent practices, showing a commitment to safeguarding user data while staying compliant with privacy laws.
Consistency and scale with Universal IDs
Effective ID bridging relies on consistency across multiple publishers. Using a Universal ID ensures that user identities are linked accurately, creating a unified view across properties. This eliminates data fragmentation and enhances targeting precision.
New revenue opportunities
Certain ID bridging solutions unlock access to unique demand pools, enabling publishers to diversify and expand their revenue streams beyond traditional cookie-based models. This can lead to better monetization, higher fill rates, and more competitive bidding for their inventory.
Adaptability for the future
ID bridging acts as a transitional tool as publishers prepare for a cookieless future. It allows them to remain profitable now while building and refining long-term first-party data strategies that are robust, scalable, and aligned with privacy norms.
Challenges and Limitations of ID Bridging
As browsers phase out third-party cookies, the effectiveness of ID bridging is expected to decline. This technique relies on linking identifiers across different environments, often using cookies as a foundation. Without new cookie IDs, the volume and success rate of bridging activities will decrease, making it harder to measure ad performance uplift.
Therefore, while ID bridging has been beneficial, it is not a sustainable long-term solution in a cookieless world.
Privacy concerns and regulations
ID bridging must comply with data protection regulations like the GDPR and the CCPA. These laws require transparency and user consent for data processing activities.
Handling user data through ID bridging involves collecting and processing personal information across platforms. This raises concerns about user consent, data minimization, and the potential for misuse. Implementing ID bridging without proper disclosure can lead to non-compliance, resulting in legal penalties and damage to user trust.
Data security and transparency risks
ID bridging can introduce data security risks, including potential breaches during the linking of identifiers across platforms. To mitigate these risks, organizations should implement encryption, access controls, and regular security audits.
Adopting a privacy-by-design approach can further enhance data security. Users should be informed about how their data is collected, processed, and shared. However, achieving this transparency can be challenging, especially when multiple parties are involved..
Cross-platform scalability issues
Maintaining accuracy in ID bridging across diverse devices and channels is challenging.
Variations in device identifiers, operating systems, and user behaviors can lead to inconsistencies. Developing standardized methods and investing in advanced technologies are essential to improve scalability and accuracy in cross-platform environments.
ID Bridging vs. Other Identity Solutions
| ID solutions | Use cases | Impact on advertisers and publishers | Examples |
| ID bridging | Maintains targeting capabilities by linking identifiers in environments lacking cookies (e.g., linking Chrome and Safari IDs). | Allows advertisers to continue using established DSP/SSP connections but requires careful disclosure. | Bridging Chrome and Safari user identifiers to maintain ad relevance and targeting. |
| ID spoofing | Used for fraudulent purposes, including ad misrepresentation and revenue manipulation. | Negative impact, introduces fraudulent activity and erodes trust between advertisers, publishers, and users. | Swapping legitimate IDs with fake ones to manipulate bidding or traffic data. |
| Unified ID 2.0. | Enables consistent targeting and measurement in a cookie-less world, often used as a replacement for third-party cookies. | Offers privacy-safe targeting and measurement with user consent, creating trusted connections with advertisers and publishers. | Hashed email-based identifiers (e.g., via login) used across devices and platforms for consistent targeting. |
| Cookie based tracking | Tracks users’ behavior across multiple websites, used for personalization and retargeting. | Historically effective but increasingly limited due to browser restrictions and privacy regulations. | Tracking user behavior using third-party cookies placed on web browsers. |
| First-party data strategies | Used for personalization, customer segmentation, and cross-channel marketing based on direct user data (e.g., behavioral data, loyalty programs). | High impact, provides rich data for targeting, improved user relationships, and cross-channel insights. | Customer data platforms (CDPs), contextual targeting, loyalty programs, authenticated user data (e.g., email logins), data clean rooms. |
ID Bridging vs. ID Spoofing
ID Bridging and ID spoofing both involve adding information to bid requests, known as bid enrichment, but they differ significantly in purpose and transparency.
ID bridging is a legitimate practice where SSPs enhance bid requests by linking user identifiers across different environments (e.g., browsers) to help advertisers better recognize and bid on users. This practice relies on full disclosure to buyers, who can review the origin of identifiers and make informed bidding decisions..
On the other hand, ID spoofing uses techniques similar to ID bridging but without transparency.
It involves falsifying or swapping identifiers, often concealing their origin and leading to potential mismatches or deceptive bidding scenarios. In short, ID spoofing is a malicious counterpart to the otherwise beneficial practice of ID bridging.
ID Bridging vs. Unified ID 2.0 vs. Cookie-Based Tracking
Unified ID 2.0 (UID 2.0) is a next-generation identifier designed to replace third-party cookies and improve transparency, privacy, and control over user data. Unlike cookies, which operate without explicit user consent, UID 2.0 is built around user-provided information that is hashed and encrypted. It emphasizes user control and transparency, aligning with new privacy standards and regulations.
Cookie-based tracking relies on small data files (cookies) stored in a user’s browser to track their online behavior, preferences, and interactions. This method has been a dominant tool for digital advertisers, enabling personalized ads and cross-site tracking.
However, cookies have come under scrutiny due to privacy concerns, prompting major browsers to phase out third-party cookies. While effective for targeting and analytics, cookie-based tracking lacks the transparency and user control now required, leading to its decline.
ID Bridging vs. Other First-Party Data Strategies
While ID bridging aims to retain targeting consistency by linking identifiers across different browsers or platforms, other first-party data strategies emphasize privacy, user engagement, and transparency. Each approach reflects a unique path for navigating identity and targeting challenges, with first-party data strategies gaining favor for their alignment with privacy regulations.
First-party data typically use data collected directly from an advertiser’s or publisher’s owned sources, such as their website, app, CRM systems, or loyalty programs. These strategies often emphasize building relationships with users while prioritizing privacy and data control.
- Customer data platforms (CDPs) aggregate first-party data from various sources (e.g., website interactions, purchases, customer support interactions) to create a unified profile for each user. Unlike ID bridging, CDPs focus on direct customer interactions and insights rather than bridging data across multiple environments.
- Contextual targeting leverages the context and content of a webpage to serve relevant ads rather than relying on user-specific identifiers. For instance, an ad for running shoes may be displayed in an article about marathon training.
- Authenticated user data involves user authentication, such as logging in with an email, to create an identifier tied to a real person. Solutions like Unified ID 2.0 are built on this model, where a user’s email is hashed and used as a persistent, privacy-safe identifier. Unlike ID bridging, which primarily relies on linking browser-specific identifiers, this enables cross-device tracking and targeting with user consent.
- On-site engagement data (behavioral data) shows how users engage with the publisher’s content or products (e.g., pages visited, clicks, or time spent on a site). This data allows segmentation and targeting without needing third-party identifiers or linking across devices/browsers.
- Data clean rooms are secure environments where multiple parties (e.g., advertisers and publishers) can match and analyze their first-party data without revealing personally identifiable information. Clean rooms enable audience insights and measurement through privacy-safe data collaboration.
Practical Applications of ID Bridging in Advertising
Programmatic advertising and real-time bidding (RTB)
In programmatic advertising, RTB allows advertisers to bid on individual ad impressions in real-time. ID bridging enhances this process by linking user identifiers across different environments. This cross-device recognition improves targeting accuracy and campaign performance.
- For example, suppose a user browses a product on a desktop and later uses a mobile device. In that case, ID bridging can connect these interactions, allowing advertisers to deliver consistent and relevant ads across devices.
Content personalization across platforms
Publishers and content providers use ID bridging to deliver personalized user experiences across multiple platforms. By unifying user identities, they can tailor content recommendations based on a user’s behavior on different devices.
- For example, a streaming service might suggest shows on a smart TV based on viewing habits from a user’s smartphone.
Multi-touch attribution models
In marketing, understanding the customer journey across various touchpoints is crucial. As we already know, ID bridging connects user interactions across devices and channels. Thus, this comprehensive view further allows marketers to attribute conversions to the appropriate touchpoints, leading to better-informed budget allocations and strategy optimizations.
- For example, recognizing that a user first engaged with a brand through a mobile ad and later converted on a desktop site helps assess each channel’s effectiveness.
Conclusion
ID bridging addresses the challenges posed by the decline of third-party cookies. Linking user identifiers across different devices and platforms enables precise targeting, consistent content personalization, and effective multi-touch attribution. It supports publishers and advertisers in maintaining user recognition and delivering relevant experiences.
While ID bridging offers many advantages, including enhanced targeting accuracy and compliance with privacy regulations like GDPR and CCPA, it has its challenges. Ensuring user privacy, achieving cross-platform consistency, and maintaining consumer transparency are crucial to successful implementation.
To ensure long-term success, industry stakeholders must prioritize privacy, standardization, and user consent while investing in robust first-party data strategies. This focus will enable a more sustainable, transparent, and privacy-respecting approach to identity management and digital advertising.
FAQs
What is the main difference between ID bridging and traditional tracking methods?
ID bridging links user identities across different devices and platforms without relying solely on third-party cookies, while traditional tracking typically uses cookies to follow user behavior across the web.
How does ID bridging impact user privacy?
ID bridging can improve privacy by using first-party data and user-consent-based identifiers, aligning with evolving privacy standards compared to cookie-based tracking.
Is ID bridging compliant with current privacy laws?
When implemented transparently and with user consent, ID bridging can comply with regulations like GDPR and CCPA, making it a privacy-conscious alternative.
How does ID bridging improve ad targeting?
By linking identifiers across platforms, ID bridging provides a consistent view of users, enhancing targeting accuracy and personalization capabilities for advertisers.
What are the primary challenges of implementing ID bridging?
Challenges include maintaining platform accuracy, achieving user transparency, and adhering to complex privacy regulations.
Can small publishers benefit from ID bridging solutions?
Yes, small publishers can use ID bridging to enhance audience targeting, attract privacy-conscious advertisers, and remain competitive in a cookieless world.
