What is Advertising Studio, and how does contact list sync to Facebook, Google, and LinkedIn work?

Advertising Studio is a Marketing Cloud product that enables you to sync Marketing Cloud audience segments to advertising platforms for targeted or suppressed advertising.
Supported platforms: Facebook/Instagram Custom Audiences, Google Customer Match, LinkedIn Matched Audiences, Twitter (X) Tailored Audiences.
Sync process:
1. Connect Advertising Studio to the ad platform's ad account via OAuth.
2. Create an Audience in Advertising Studio linked to a Marketing Cloud data extension or subscriber list.
3. Advertising Studio hashes PII (email, phone) before sending to the ad platform; the platform matches hashed records to its user base — raw data never leaves Salesforce.
Minimum audience sizes: Facebook requires at least 100 matched users; Google requires 1,000. Audiences below these thresholds are not activated on the ad platform.
Journey Builder integration: An Advertising Audience activity in Journey Builder can add or remove a contact from an ad audience as they progress through a journey (e.g., remove from retargeting after purchase).