Retargeting is advertising that re-engages people who previously interacted with a website, ad, product, or brand.
It matters because most visitors do not convert on the first visit. Retargeting terminology helps teams create thoughtful follow-up sequences, avoid wasted impressions, and respect audience exclusions and privacy expectations.
Example
A visitor reads a product comparison but leaves without buying. If they are eligible for an advertising audience, a later ad can remind them about that product; recent purchasers can be excluded from the same acquisition message.