The metric most often reported as progress
Impressions are easy to grow and easy to misread. Publishing more pages, or ranking for more long-tail variations, raises impressions without raising traffic — and the chart looks like success.
This site is its own example: impressions rose 639% over a period in which clicks stayed flat. What that measured was wider exposure at positions nobody clicks, which is not the same as growth, and treating it as growth would have justified continuing exactly the strategy that produced it.
Read impressions with position and clicks beside them. Impressions up and average position down means you are surfacing for more, worse queries. Impressions flat and clicks up means the pages you already rank for are earning better click-through — usually the more valuable movement.