Glossary
What is first-party data?
First-party data is information a business collects directly from its own audience on its own properties: website visits, orders, sign-ups, email addresses and app activity. It contrasts with third-party data, which is collected by another company across sites and apps it does not own.
In tracking, the first-party/third-party distinction is mostly about context: cookies set by your own domain (or a subdomain like track.yourstore.com) are first-party and treated far more leniently by browsers than third-party cookies, which Safari and Firefox block by default and the industry as a whole is phasing down.
For advertisers, first-party data is what still works: click IDs captured on your landing pages, a durable visitor identity on your own domain, and the emails and phone numbers customers give you at checkout. Hashed and attached to server-side events, these identifiers drive match quality and attribution on Meta, Google and TikTok.
First-party does not mean unregulated. Under GDPR it is still personal data and requires a lawful basis and honest consent handling. The advantage is architectural, not legal: data you collect on your own domain, with your customer’s knowledge, is durable in a way third-party tracking no longer is.