What it is
You give Google a customer list, a CSV of hashed emails or phone numbers, and Google matches it against signed-in users to build an audience segment. That segment can then be used three ways: as a targeting audience, as an observation audience, or as an exclusion. Lists have a membership duration and need at least 100 matched, recently updated members to stay active.
The exclusion use most accounts miss
The most underused move is exclusion. Upload the leads your sales team already disqualified, spam, tyre-kickers, competitors, repeat bot form-fillers, and apply the list as a negative audience so you stop paying to re-acquire people you have already rejected. Unlike targeting, which requires $50,000 of lifetime spend and 90 days of account history, using Customer Match for exclusions is open to every policy-compliant advertiser from day one. We walk through the whole play in stop paying to re-acquire leads your sales team already rejected.