Cold, warm, new-but-similar: the three audience families
"Core is cold, custom is warm, and lookalike is new but similar."
Saved audiences are built from location, age and interests. Custom audiences come from "your sources" (website visitors via the pixel - "the heart of retargeting" - or an uploaded customer list) or "Meta sources" (people who watched your video, opened your lead form, visited your Instagram profile). Engagement audiences work even without a website.
Choosing the family decides how warm the message can be.