Which metric describes the ratio of impressions you've received to the estimated impressions available?

• A. Click-through rate
• B. Impression Share
• C. Cost per view
• D. Return on ad spend

Answer: (B)

Impression share tells you how much of the eligible impressions your ads actually received. It’s the ratio of impressions you served to the estimated impressions available in the auctions you were eligible for, reflecting how often your ads appeared relative to potential reach. This metric helps you understand visibility and opportunities to improve reach by adjusting budgets, bids, or ad quality so you capture more of the available impressions.

The other metrics measure different things: click-through rate looks at how often people click relative to impressions, cost per view focuses on expense per view, and return on ad spend compares revenue to cost. None of these describe the proportion of actual impressions you got out of what you could have potentially shown.