Definition Custom audience sources vary: uploaded customer list (email, phone), website visitors (pixel or tag), app users (SDK), video viewers, Instagram/Facebook engagers.
How it works The platform hashes source data and matches it against its own user pool. Matched users form the custom audience pool. The match rate depends on data quality: 30-70% is typical. Pixel- or tag-based pools update in real time. Uploaded lists retain for up to 14 days. Custom audiences also feed audience exclusions.
Where you see it in Scope Trends The **Audience Management** tab lists every custom audience's state, member count, and last update date. The **Cross-Platform Match** report shows the distribution of the same user across Meta, Google, and LinkedIn.
Frequently asked questions **Is uploading a customer list legal?** Yes with explicit consent from the data subject. GDPR and KVKK are enforced by every platform.
**How far back does a pixel-based audience reach?** Meta defaults to 180 days, Google to 540 days. 30 days is the starting point for retargeting.