First vs Third Party
Data & TrackingAlso: First-Party Data vs Third-Party Data · First-Party vs Third-Party Cookies
Quick definition
First-party data is information collected directly from your own customers through forms, purchases or your own website tracking. Third-party data is collected by an outside company, aggregated across many sources, then licensed or sold to advertisers. The distinction matters because consent, ownership and reliability differ sharply between the two.
How it varies across Australia
Australian businesses that lean heavily on first-party data collection score noticeably higher on data and tracking maturity than those still dependent on third-party audiences. The gap is widening as third-party cookie support keeps eroding across browsers.
See data and tracking scores across Australian industries →The two data types
Data your customer gives directly to you, through forms, purchases or your own tracking.
You own the consentData collected by someone else and licensed or sold to you, often via ad platforms.
Consent is inherited, not directWhat it actually means
Imagine two guest lists. The first is one you built yourself, from people who gave you their number at your own event. The second is a list you bought from a promoter who collected it across a dozen different parties you've never been to. That's the split between first-party and third-party data.
First-party data is anything a customer gives you directly: form fills, purchase history, email signups, on-site behaviour tracked with your own pixel or data layer. You own the relationship and the consent that comes with it.
Third-party data is collected by someone else, aggregated, then sold or licensed to you. Ad networks used it for years to build audience segments and retarget people across the web using third-party cookies. Browser cookie deprecation and stricter mobile tracking limits have been steadily cutting off that supply.
The practical effect: first-party data has become the asset every serious marketing team is trying to grow, because it survives every platform change. Third-party data still exists through data co-ops and contextual targeting but it's thinner, costs more and answers fewer questions than it used to.
The businesses caught out are the ones who built their entire retargeting strategy on third-party cookies and never invested in owning a direct channel to their own customers.
Third-party data was always borrowed. First-party data is the only kind you actually own.
How it shows up
First-party data shows up in your CRM, your email list, your on-site data layer and your loyalty programme. It's the segment you can message directly tomorrow morning without paying a platform for access.
Third-party data shows up in ad platform audience builders and look-alike modelling, or any audience you didn't build from your own list. It also shows up as a gap: when your retargeting pool suddenly shrinks and nobody can explain why, that's third-party signal loss, not a budget problem.
The Australian context
Australia's Privacy Act reforms are pushing the balance further toward first-party data. Tighter consent requirements under the amended Act, plus ACMA's enforcement of the Spam Act on email and SMS marketing, mean third-party lists bought without a clear consent chain are a compliance risk as much as a targeting one.
Local advertisers relying on shrinking third-party signals from major ad platforms also face a smaller addressable market than US counterparts, since Australia's population means look-alike audiences hit their ceiling faster. That makes an owned list, even a modest one, proportionally more valuable here than in a market ten times the size.
Where people get this wrong
Related terms
Common questions
Is first-party data always better than third-party data?
For targeting accuracy and compliance, yes. Third-party data still has a role for reaching entirely new audiences you have no relationship with, but it should never be the foundation of your marketing, only a supplement to a first-party base.
What's the difference between first-party and zero-party data?
First-party data includes anything collected through a customer's interaction with you, including inferred behaviour like browsing history. Zero-party data is narrower: information a customer explicitly and voluntarily shares, like stated preferences or survey answers.
Are third-party cookies actually gone?
Not entirely. Browser support has been phased out unevenly, with Safari and Firefox further along than Chrome. The direction is clear even if the timeline has shifted repeatedly, so building around cookies as a long-term strategy is a mistake.
How do I start building first-party data if I don't have much?
Start with the exchange every visitor already makes with you: order confirmations, account creation, newsletter signup. Add a clear reason for someone to hand over an email, like a discount or useful content, and make consent explicit from day one.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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