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Part 1 - Foundations of Digital Advertising & Measurement

  • Why This Primer?
  • Introduction
  • Chapter 2: Core Concepts
    • What is AdTech?
    • How Data Moves in AdTech
    • Important Numbers for Online Ads
  • Chapter 3: Measurement Fundamentals
    • Why It’s Important to Measure (and Why It’s Harder Than You Think)
    • Counting Impressions: Tags, Pixels, and Logs
    • The Messy Truth About Measuring ROI
  • Chapter 4: User Identification
    • Cookies (Not the Good Kind)
    • The Great Cookie Flip-Flop (Chaos in Motion)
    • Life After Cookies (Other Ways to Identify Yourself)
    • Device IDs vs. People IDs: Who Are We Even Following?

Part 2 - Programmatic Advertising & Data Activation

  • Chapter 5: Introduction to Programmatic Advertising
    • What is Programmatic Advertising?
    • The Millisecond Auction: Bidding in Real Time
    • DSPs, SSPs, Ad Exchanges, and DMPs
  • Chapter 6: Data in AdTech
    • Data Types in AdTech (First, Second, and Third-Party)
    • DMPs (Data Management Platforms) - The Old Guard
    • CDPs (Customer Data Platforms)
    • Targeting and Segmentation

Part 3 - Modern Challenges & Future Trends

  • Chapter 7: Privacy and Regulation
    • Privacy Issues in AdTech
    • Privacy Rules (The Laws With Teeth)
    • CMPs (Platforms for Managing Consent)
    • Privacy by Design
  • Chapter 8: Programming in AdTech
    • Programming in AdTech
    • Basic Ad Server
    • Header Bidding Basics
    • Real Time Bidding (RTB) Simulation
    • Creative A/B Testing
    • Deal IDs & Private Marketplace (PMP)
    • Client-Side vs Server-Side Tagging
  • AI & Machine Learning in AdTech
    • AI Applications in AdTech
    • Algorithmic Bidding
    • Predictive Analytics in AdTech

Appendices

  • Conclusion: The AdTech Evolution Continues
  • Glossary
  • Appendix: Resources, Tools & Further Reading
  • Daily AdTech News
  • References
  • .md

The Great Cookie Flip-Flop (Chaos in Motion)

Contents

  • Cookie Apocalypse
  • Stutus in 2025
  • What This Actually Means for Advertisers
  • First-Party Data is King
  • The Uncomfortable Truth

The Great Cookie Flip-Flop (Chaos in Motion)#

Google announced they were killing third-party cookies in Chrome. They then delayed it. Then delayed it again. Then said “actually, we’re keeping them but making them opt-in”?

For those in the industry, this is an ongoing saga.

Cookie Apocalypse#

Around 2020, Google—the company that owns both the biggest browser (Chrome) and the biggest ad business (Google Ads)—announced they’d phase out third-party cookies by 2022.

User privacy was cited as the reason but the real reason was regulatory pressure.

This procrastination went on from 2020 to 2025 when they declared they were keeping cookies but users have to opt-in.

Hordes of companies has invested in ‘cookieless solutions’ only to be told it was not happening.

Stutus in 2025#

As of writing this, google has announced a default opt-out system.

Default Opt-Out System When you access the site, a prominent prompt asking if you wish enable third-party cookies shows up. Nobody I know chooses to enable this.

So essentially while 3rd party cookies still exist , few enable them.

What This Actually Means for Advertisers#

If only 5-20% of Chrome users opt-in to third-party cookies (optimistic estimate), your tracking and targeting capabilities just lost 80-95% of reach in the world’s most popular browser. This has implications to

  • ** Retargeting ** as users cannot be tracked across sites

  • ** Attribution ** as its hard ot track which ads led to conversions -** Audience Targeting** is harder as its hard to collect audiences -Frequency capping is poor as the same user keeps seeing the same ads

First-Party Data is King#

Building your first party i.e. 1P data is key to mitigate the above.

First-party data means:

  • Email addresses and phone numbers provided directly with customer consent

  • Login or registration data from your own website or app

  • Purchase history and browsing behavior on your website

  • Any other data you have collected via customer relationships

Companies that invested in loyalty programs, registration flows. email lists, and direct relationships with proper customer consent mechanisms are winning. Companies that relied entirely on third-party cookies? They’re scrambling.

The Uncomfortable Truth#

Third-party cookies were always a hack—a workaround that gave advertisers power they probably shouldn’t have had. The fact that a random ad tech company could track your behavior across thousands of websites without you really knowing was wild.

With the advent of AI and newer channels to market to people, more privacy-respecting systems are a must. Everyone’s still figuring it out.

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Cookies (Not the Good Kind)

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Life After Cookies (Other Ways to Identify Yourself)

Contents
  • Cookie Apocalypse
  • Stutus in 2025
  • What This Actually Means for Advertisers
  • First-Party Data is King
  • The Uncomfortable Truth

© Copyright 2025 CC BY-NC 4.0.

© Copyright 2025 CC BY-NC 4.0.
Licensed under CC BY-NC 4.0.
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