Search Popularity Score is a measure of how often a keyword is searched — surfaced on a roughly 5-to-100 scale in Apple Search Ads — used to judge whether a term is worth targeting.
Apple doesn't publish raw search volumes, but Apple Search Ads exposes a popularity score (commonly seen on a 5–100 scale) that estimates relative demand for a keyword. ASO practitioners lean on it as the closest official read on volume: a higher score means more people search the term, so ranking for it can deliver more impressions — if you can actually rank. Most third-party ASO tools build their volume estimates on top of this signal.
Score alone isn't a target list, though. A very popular term is usually fiercely contested, so a mid-popularity phrase you can realistically rank for often drives more installs than a top-popularity one where you'd sit on page two. The useful move is to weigh popularity against difficulty and intent together, picking terms with enough demand and a genuine path to a high rank.
Example
"Photo editor" shows a popularity near the top of the scale but is dominated by giants; a startup instead targets "photo collage maker" at a moderate score, where the demand is real and a top-three rank is achievable.