Glossary/Audience data/Third-party data
What is third-party data in advertising?
What third-party data is, where it comes from, how it compares with first- and second-party data, and why buyers are moving away from it.
Written by Samhub with the help of AI·Updated 13 Oct 2026·3 min readThird-party data is data collected by a company with no direct relationship to the people it describes, usually gathered across many sites and sold to advertisers as audience segments.
First-, second- and third-party data
| Source | Accuracy | |
|---|---|---|
| First-party | Your own readers | High |
| Second-party | A partner’s own data | High |
| Third-party | Aggregated from many sites | Varies |
Why it is declining
Much third-party data relied on third-party cookies, which browsers block or limit. Privacy rules also demand clear consent and transparency, which is hard to prove for data collected far from the source.
16 pages for publishers, with a checklist for data, programmatic and direct sales.
The opportunity for publishers
As third-party data fades, buyers look for audiences from sources they can trust. Publishers with first-party data and consent offer exactly that.
Addressability at Stampen Media after moving its reader data into one layer with Samhub.
Frequently asked questions
No, but it must be collected and used under GDPR, which makes it harder to use in the EU.
From data providers that collect it across sites, apps and other sources, or buy it from others.
It varies. It is often modeled and can be out of date.
First-party publisher data, second-party partnerships and contextual targeting.
Related terms
Data you collect directly from your own readers.
Cookies set by another domain than the site you visit.
Collects and segments audience data for advertising.
Targeting ads based on the content of the page.
One EU-based platform to collect, unify and enrich your first-party data, installed with one script.
- A walkthrough with your own data
- Built for publishers and media houses
- 30 minutes, no commitment
Turn your audience data into more revenue
Get the Media Monetization Playbook: how media houses turn first-party data into higher CPMs, data deals and direct sales. With checklists for every step.
