Custom Audience is an advertiser-owned or platform-built audience such as website visitors, customer lists, or engagement audiences.
It matters because Reddit rewards relevance, authenticity, and community context. Brands that understand the platform’s terminology can build campaigns that feel useful to users instead of interruptive.
Example
A business builds an eligible audience from prior website activity and excludes recent purchasers where supported. It verifies the source, retention period, and permissions before using the audience in a new campaign.