Audiences & targeting
Retargeting
Retargeting (or remarketing) serves ads to people who have already interacted with the brand: site visitors, video viewers, cart abandoners, CRM contacts. It converts efficiently because the audience is warm, which also makes it easy to over-credit and over-fund.
In practice
Retargeting harvests demand that other activity created. Its strong last-click numbers are partly borrowed; incrementality thinking keeps its budget honest.
Frequency caps and sensible recency windows matter here more than anywhere - chasing a cart abandoner for six weeks is a brand cost, not a performance tactic.