Unified ID 2.0
A privacy-first system that lets marketers identify and reach individual customers across websites and apps without using third-party cookies. It replaces the old cookie-based tracking method with encrypted, consent-based identifiers that work across the open web.
Full Explanation
The Problem It Solves
For decades, marketers relied on third-party cookies to track users across the internet. You'd place an ad on one site, then follow that user to another site to retarget them. But browsers are killing third-party cookies—Safari and Firefox already block them, and Chrome is phasing them out. This creates a massive gap: how do you know who your customers are across different digital properties if you can't track them with cookies?
Unified ID 2.0 (UID2.0) solves this by creating a persistent, privacy-safe identifier that works without cookies.
How It Works in Marketing
UID2.0 uses hashed email addresses (encrypted, one-way conversions) as the foundation. When a user logs into a website or app, their email gets hashed and converted into a unique token. That token travels with them across partner sites and apps—allowing you to recognize them, serve personalized ads, and measure campaign performance.
Key differences from cookies:
- Consent-based: Users must opt in; it respects privacy regulations like GDPR and CCPA
- Encrypted: The identifier is hashed, not readable as plain text
- Cross-device: Works on mobile, desktop, and connected TV
- First-party controlled: You own the relationship; it's not a third party tracking
Real-World Example
A customer visits your e-commerce site and logs in. Their email is hashed into a UID2.0 token. Later, they browse a news site that's part of the UID2.0 ecosystem. Because both sites recognize that token, you can serve them a personalized ad for the product they abandoned. You measure the conversion without ever knowing their email address across that news site.
What This Means for Tool Selection
When evaluating marketing platforms, ad tech, and analytics tools, ask: Do they support UID2.0? Can they activate audiences using UID2.0 tokens? Do they help you collect and hash first-party data correctly? Tools that integrate UID2.0 will be essential as third-party cookies disappear. This isn't optional—it's your bridge to a post-cookie world.
Why It Matters
Business Impact for Marketing Leaders
UID2.0 directly protects your ability to measure ROI and personalize at scale. As cookies disappear, marketers without a UID2.0 strategy face a 30-50% drop in ad targeting accuracy and campaign attribution. This translates to wasted ad spend and lower conversion rates.
Competitive and Budget Implications
- Audience reach: UID2.0 reaches ~60% of the open web (and growing), so early adoption gives you access to inventory competitors may miss
- Cost efficiency: First-party, consent-based identifiers reduce wasted impressions on irrelevant users, improving cost-per-acquisition (CPA)
- Regulatory safety: UID2.0 is built for compliance, reducing legal risk and avoiding fines
- Vendor lock-in prevention: Unlike proprietary walled gardens (Google, Meta), UID2.0 is an open standard, giving you negotiating power with ad platforms
Practical Implication
Start auditing your martech stack now. Identify which tools support UID2.0 activation and which require replacement. Budget for first-party data infrastructure (email collection, consent management) in 2024–2025. Teams that move early will maintain targeting precision; those that wait will face a sudden drop in campaign performance.
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Related Terms
First-Party Data
Information you collect directly from your own customers and website visitors—like email addresses, purchase history, and behavior on your site. It's the most reliable data you own, unlike third-party data bought from brokers or collected by other companies.
Customer Data Platform (CDP)
A CDP is a software system that collects customer data from all your marketing, sales, and service tools into one unified profile. Think of it as a single source of truth about who your customers are, what they've done, and what they're likely to do next—so you can personalize marketing at scale without manual work.
Identity Resolution
The process of recognizing the same person across different devices, channels, and touchpoints—even when they're not logged in. It's how marketing systems know that the person browsing on mobile is the same person who opened your email yesterday.
Cross-Device Tracking
The ability to recognize and follow the same person as they move between their phone, tablet, laptop, and other devices. It lets you understand the complete customer journey instead of seeing fragmented visits on separate devices.
Related Tools
Related Reading
Get the Full AI Marketing Learning Path
Courses, workshops, frameworks, daily intelligence, and 6 proprietary tools — built for marketing leaders adopting AI.
Trusted by 10,000+ Directors and CMOs.