Impressions

An impression is counted every time your ad is displayed on a search results page or product page — whether or not anyone clicks it.

Impressions tell you how often you're winning auctions. Low impressions on a keyword you care about usually mean your bid is below the level needed to show, your budget runs out early in the day, or the keyword simply has little search volume.

High impressions with few clicks (low CTR) point at relevance or listing problems instead. The diagnostic order matters: first get impressions (bid/budget), then clicks (relevance/creative), then orders (listing/price).