publisher domains are grouped into two separate tiers.  Domains in both tiers are continuously reviewed and monitored for traffic quality and performance.

Tier 1: Domains with a long-standing history of consistent, good quality traffic.

Tier 2: Generally smaller or new domains whose traffic may not match that of Tier 1.

CPC minimums are slightly higher for Tier 1 and lower for Tier 2.

If you have a support question or bug report, please contact our support team.