⚡ Tier 2 - ImportantID: viewabilityRate
Viewability Rate (MRC Standard)
% of served ad impressions that were actually visible to a human eye on screen
In Simple Words (Zero Jargon):
The percentage of your ads that were actually seen by real people on screen (at least 50% of the ad visible for 1+ second) rather than loaded below the fold where nobody scrolled.
Official Mathematical Equation
Viewability% = (Viewable Impressions ÷ Total Served Impressions) × 100 (Standard: 50% pixels in view for $\ge 1$s display / $2$s video)
Why It Is Critical
Serving an unseen ad below the fold wastes 100% of the budget. Marketers should set a minimum viewability floor (commonly 70%+) in DSP settings to automatically exclude ghost impressions.
What You Get: Confidence that advertising budget is buying impressions a human actually saw on screen, not just ghost server calls.