“If we want to really simplify behavioral targeting, a behavior can be distilled to three attributes:
The event: Is this a visit to Kelley Blue Book or a visit to Yahoo! Autos. A visitor to one or the other could perform differently. Recency: Was it a week ago or a month ago. Was it an hour ago? True story: Retargeting cookies you dropped in the last hour perform a zillion times better than anything else you are doing. Are you watching those? Are you segmenting them out? Frequency: Did they visit twice? Three times? That performs differently.”