ASO glossary

    appXL ResearchUpdated

    This glossary defines the app store optimization terms that appear in App Store Connect, Google Play Console and everyday ASO work, grouped by theme: discovery and ranking, metadata fields, conversion and creative, testing and measurement, and reviews and quality. Each entry is a single self-contained sentence, so a term can be quoted on its own. Where Apple and Google use different names for the same idea — custom product pages versus custom store listings, in-app events versus promotional content — both names are given against one definition.

    Key takeaways

    • Terms are grouped by theme rather than alphabetically, so related concepts sit together.
    • Where the two stores name the same idea differently, both names appear against one definition.
    • Each definition stands alone and can be quoted without the rest of the page.

    Discovery and ranking

    • ASO — app store optimization: the practice of improving an app's visibility and conversion inside app store search and browse.
    • Indexation — whether a store's search engine reads a given field; Apple indexes the name, subtitle and keyword field, Google Play indexes the title and both descriptions.
    • Keyword field — Apple's hidden 100-character, comma-separated list of terms, invisible to users but fully indexed.
    • Combination — Apple builds searchable phrases from separate indexed words, so 'meal' and 'planner' can rank for 'meal planner' without the phrase appearing anywhere.
    • Search visibility score — a vendor-calculated index of how much store search traffic your ranked keyword set is estimated to reach.
    • Browse traffic — installs that come from category charts, editorial placements and recommendation shelves rather than search.
    • Chart rank — position in a category or overall top-list, driven mainly by recent download velocity.
    • Featuring — editorial placement by Apple or Google on the Today tab or a Play collection.
    • Similar apps — the recommendation shelf on a product page, influenced by category, metadata overlap and co-install behavior.
    • Brand defence — deliberately ranking for your own brand term so competitors cannot occupy that result.
    • Cannibalisation — two of your own listings competing for the same query, splitting impressions between them.
    • Long tail — low-volume, specific queries that convert well and are far easier to rank for than head terms.

    Metadata fields

    • App name — the 30-character iOS title field, the single highest-weighted indexed element.
    • Subtitle — Apple's 30-character line under the name; indexed and visible in search results.
    • Title — Google Play's 30-character equivalent of the app name, also the highest-weighted Play field.
    • Short description — Play's indexed 80-character summary shown above the fold.
    • Full description — Play's indexed 4,000-character body; on iOS the equivalent field is not indexed at all.
    • Promotional text — Apple's 170-character line, editable without shipping a build, not indexed.
    • What's New — the release-notes field on both stores, used for update messaging rather than ranking.
    • Bundle ID / package name — the immutable technical identifier of the app on iOS and Android respectively.
    • Category — the primary and secondary classification that determines which charts and browse surfaces you appear in.
    • Localization — a per-storefront copy of the metadata and creative, each with its own indexed fields.
    • Locale group — a set of storefronts where more than one language locale is indexed, letting one extra locale extend keyword coverage.

    Conversion and creative

    • Conversion rate — product page views divided by installs; a direct ranking input on both stores.
    • Tap-through rate — the share of people who see you in search results and open the product page.
    • Product page — the full store listing a user lands on before installing.
    • CPP (custom product page) — one of up to 35 alternate iOS product pages, each with its own URL, screenshots, video and promo text.
    • Custom store listing — Google Play's counterpart to a CPP, targeted by country, audience or campaign instead of by URL.
    • PPO (product page optimization) — Apple's native A/B test for icon, screenshots and preview video.
    • Store listing experiment — Google Play's A/B test, which can vary text as well as graphics.
    • App preview — the autoplaying muted video on an iOS product page.
    • Feature graphic — Play's 1024×500 banner, required for several placements.
    • First impression frame — the panel visible in search results before any swipe, where most of the conversion decision happens.
    • IAE (in-app event) — a time-boxed, indexed event card on an iOS product page; Play calls the equivalent promotional content.

    Testing and measurement

    • Uplift — the percentage change in conversion attributed to a tested variant against the control.
    • Confidence interval — the range a test result is likely to sit in; a range crossing zero means no proven effect.
    • Statistical significance — the threshold at which a measured difference is unlikely to be chance alone.
    • Novelty effect — a temporary lift caused purely by a change being new, which fades once repeat viewers adjust.
    • Impressions — how many times your app appeared in a store surface.
    • Product page views — how many people opened the full listing.
    • Install rate — installs divided by impressions, the end-to-end funnel measure.
    • Retention (D1 / D7 / D30) — the share of installers still active after one, seven or thirty days; a Play ranking input.
    • Uninstall rate — the share of installers who remove the app, weighed negatively by Google Play.
    • LTV — lifetime value, the total revenue expected from an average installed user.
    • CPI — cost per install in a paid campaign, the benchmark organic ASO is usually measured against.
    • Attribution — determining which source produced an install, usually via an MMP.
    • MMP — mobile measurement partner, the third-party service that attributes installs and in-app events to campaigns.

    Reviews, ratings and quality

    • Rating — the star average shown in search results and on the product page; a strong influence on tap-through.
    • Rating prompt — the store-provided in-app request for a review, which Apple limits to three times per year per user.
    • TTR (time to respond) — how quickly a developer replies to reviews, a factor in Play's quality assessment.
    • Review velocity — the rate of new reviews arriving, which affects how quickly the visible average moves.
    • Sentiment analysis — classifying review text by theme and tone to find the recurring reasons for low ratings.
    • Android Vitals — Google Play's technical quality dashboard; excessive crash or ANR rates suppress visibility.
    • ANR — 'application not responding', an Android event where the UI thread blocks long enough for the system to intervene.
    • Crash rate — the share of sessions ending in a crash, thresholded by Play for bad-behavior treatment.
    • Metadata rejection — a review rejection caused by store-listing content rather than app functionality.
    • Keyword stuffing — repeating terms beyond natural use, which breaches both stores' policies and does not improve ranking.
    • Incentivised installs — paying users to install or review, prohibited by both stores and grounds for removal.
    • Rank manipulation — artificially inflating install or review volume to move charts; detected and penalised by both stores.

    Frequently asked questions

    What does ASO stand for?

    App store optimization — improving an app's visibility in app store search and browse, and its conversion rate once found.

    What is the difference between a CPP and PPO?

    A custom product page is an alternate page you send specific traffic to; product page optimization is Apple's A/B test that measures creative variants against your default page. CPPs target, PPO tests.

    What is Apple's keyword field?

    A hidden 100-character comma-separated field in App Store Connect. Users never see it, but Apple indexes every term in it for search.

    appXL Research

    App Store Optimization Research Team

    The appXL research team analyzes App Store and Google Play ranking data across the apps our agent manages, and publishes what it finds.