How many media were active on a given day—the count of channels, placements, and linked live events (such as UND hockey) that ran that day. The teal Media line at the top of the flight view charts this day by day.
Depth is the times-seen ratio: how often an account in a medium’s audience is estimated to have been exposed to the ad (saturation), not raw impressions.
The × numbers in the flight grid are depth at a finer grain—not a raw impression count.
Reach in the Lifetime column is how many accounts (unique viewers or profiles) were reached in that medium—not raw impressions. Radio uses spots in that column instead of account counts; direct mail uses households. Some lines are tagged Sample (Meta and YouTube windows built from flight totals) or Estimated (radio listeners and AET account stand-ins until platform or rate-card numbers replace them).