General Terms
Custom Audiences
Targeted audience segments created from first-party data and platform capabilities.
Definition
Custom audiences are specialized targeting segments built using first-party data, platform tools, and advanced targeting capabilities. These audiences can be created through various methods including customer lists, website behavior, app activity, engagement data, and lookalike modeling to reach both existing customers and similar high-value prospects.
Examples
Lookalike audiences based on top 1% of customers
Website visitor retargeting segments
Custom audiences from email subscriber lists
Interest-based targeting for prospecting
Frequently asked questions
Common questions about Custom Audiences, answered.
What are custom audiences?
Custom audiences are targeting audiences built from an advertiser's own (first-party) data — customer lists, website visitors, app users, or people who engaged with your content. Uploaded or matched into an ad platform, they let you target people who already have a relationship with your brand, powering retargeting and customer marketing, and serving as the seed for lookalike audiences.
What are common types of custom audiences?
Customer lists (emails/phone numbers matched to platform users), website-visitor audiences (via a pixel/tag, often segmented by page or action), app-activity audiences, engagement audiences (people who interacted with your videos, posts, lead forms, or profile), and combinations with exclusions. Each lets you reach a specific group defined by their actual relationship to your brand.
How are custom audiences used?
Primarily for retargeting (re-engaging visitors and cart abandoners), customer marketing (upsell, cross-sell, retention to existing customers), exclusions (suppressing converters or current customers from prospecting), and as seed audiences for lookalikes. Because these people already know you, custom-audience campaigns typically use warm-audience creative — objection handling, offers, reminders — rather than cold awareness messaging.
What's the difference between custom and lookalike audiences?
A custom audience is people from your own data who already have a relationship with you. A lookalike (or similar) audience is new people the platform finds who resemble a custom-audience seed — used to prospect for new customers similar to your best ones. Custom audiences re-engage people you know; lookalikes expand reach to people like them. Lookalikes are built from custom-audience seeds.
What privacy considerations apply to custom audiences?
Significant ones. Uploading customer data must comply with privacy laws (consent, data handling) and platform policies, and signal loss from cookie restrictions and tracking-prevention has reduced the reach and match rates of pixel- and list-based audiences. Best practice is to use properly consented first-party data, rely on durable first-party signals (e.g. server-side tracking, hashed lists), and respect user choices — privacy compliance is both legal and increasingly a performance necessity.
