Glossary · Updated 2026

App Store Optimization Glossary

Twenty core ASO terms used in Google Play Console and the Apple App Store, defined in plain English. Each term is anchored for direct citation. Companion product: IOn Emit.

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ASO ASO Score Short Description Long Description Listing Experiment Install Velocity Keyword Density Conversion Rate Tap-Through Rate Retention Rate Pre-Launch Report Testing Tracks Data Safety Section Feature Graphic App Icon Localization Bundle ID / Package Name Indexed Keywords Custom Store Listing Android Vitals
ASO (App Store Optimization)
aka: app store SEO

The discipline of improving an app's visibility and conversion rate in app stores (Google Play, Apple App Store). ASO covers discoverability (ranking in search and category browse) and conversion (turning a store listing view into an install). It is the mobile-app equivalent of SEO, but with fewer signals, faster feedback loops, and stricter character limits.

ASO Score

A composite metric (varies by tool) that estimates how well a store listing is optimized across the levers ASO tooling can measure: metadata completeness, keyword coverage in title and descriptions, screenshot count and quality, ratings, and review velocity. It is not a Google or Apple ranking signal — it is a tool-specific health score. A high ASO Score correlates with, but does not cause, better rankings.

Short Description
Google Play only · 80 character limit

The 80-character summary shown directly under the app icon on the Google Play store listing, above the "more" expander. It is the single highest-leverage ASO field on Google Play: it is one of the first things visible, it is heavily weighted in conversion, and it is indexed for search. The Apple App Store has no direct equivalent — iOS uses the Subtitle field (30 characters) and the Promotional Text field (170 characters) for similar purposes.

Long Description
Google Play: 4,000 chars · Apple App Store: 4,000 chars

The full-length app description shown when a user taps "more" on the store listing. Indexed for search by Google Play (with diminishing weight after the first ~250 characters); not indexed for search by Apple. Apple App Store treats the long description as conversion copy only. Both stores allow rich formatting via line breaks but no HTML.

Listing Experiment
aka: store listing experiment, A/B test (Google Play); Product Page Optimization (Apple)

A native A/B test of store listing assets (icon, screenshots, short description, feature graphic) run inside Play Console or App Store Connect. Splits installer traffic between two or more variants and reports statistical winners. Google Play requires roughly 1,000 installs per variant per day for a statistically valid result within 7–14 days. Apple's Product Page Optimization allows up to 3 alternate page treatments.

Install Velocity

The rate of installs over a recent time window (typically 24–72 hours). A heavily weighted Google Play search-ranking signal: an app with a sudden install spike will temporarily rank higher than its absolute install count would predict. Velocity is why launch windows, press coverage, and feature placements compound: the boost itself drives more visibility, which drives more installs.

Keyword Density

The frequency of a target keyword (or its variants) across indexed listing fields. Google Play indexes the app title, short description, and long description; keyword stuffing is penalized algorithmically (the indexer is generally smarter than tools assume). Apple's App Store uses a dedicated 100-character keyword field instead, and the long description is not indexed. Density alone does not rank an app — relevance, conversion, and retention matter more.

Conversion Rate (Store Listing)
aka: install rate, CVR

The percentage of store listing visitors who install the app. Reported by Play Console as Acquisition Reports > Store Listing Conversion. A healthy installed-from-search rate is typically 25–35% on Google Play and 30–40% on Apple App Store for mid-tier categories. Low conversion with high impressions usually points to icon, screenshots, or short description issues — not keyword relevance.

Tap-Through Rate (TTR)
aka: CTR (click-through rate)

The percentage of users who tap into a store listing after seeing it in search results or browse. Driven almost entirely by the icon, title, and (on Apple) the first screenshot visible in the search result card. Improving TTR has compounding benefit: more taps surface the listing to the conversion funnel and signal relevance back to the ranking algorithm.

Retention Rate

The percentage of users who return to the app on subsequent days. Reported by Play Console (Day 1, Day 7, Day 30) and App Store Connect. Both stores use retention as a ranking signal — an app with poor Day 1 retention will lose ranking even with strong install velocity. Median Google Play Day 1 retention is around 25%; Day 30 around 5%. Apps significantly above these benchmarks rank materially higher.

Pre-Launch Report
Google Play only · auto-generated

An automated test run by Google's Firebase Test Lab whenever a new APK or AAB is uploaded to internal/closed/open testing. Crawls the app on a set of real devices, captures screenshots, and reports crashes, accessibility issues, security warnings, and performance regressions. Pass it before promoting to production — failures here will block prod release even if the binary itself is valid.

Testing Tracks (Internal, Closed, Open)
Google Play release channel structure

Google Play's tiered release channels:

  • Internal Testing — up to 100 named testers, available within minutes, no review.
  • Closed Testing — up to 200 testers per email list (now requires 12 testers for 14 days before a first prod release for new developer accounts).
  • Open Testing — public beta, listed in Play Store.
  • Production — live release.

Apple's equivalents are TestFlight (internal up to 100, external up to 10,000) and App Store production.

Data Safety Section
Google Play required · Apple equivalent: Privacy Nutrition Labels

A mandatory disclosure form in Play Console declaring exactly what data the app collects, what it shares with third parties, and how it is protected (encryption in transit, deletion controls, etc.). Inaccurate disclosure is a top-five rejection cause and can result in delisting after the fact if Google's review system flags a mismatch between declared data handling and observed network traffic.

Feature Graphic
Google Play · 1024 × 500 px · required

A required 1024×500 pixel banner image shown at the top of a Google Play store listing on mobile and used in Featured placements. Should communicate the core value of the app at glance, avoid text smaller than 24px (it scales), and not include device frames (Google adds those automatically). Required for submission; apps without one cannot be published.

App Icon (ASO context)
Google Play: 512 × 512 px · Apple: 1024 × 1024 px

The single highest-leverage visual asset for tap-through rate. Both stores require a high-resolution square icon. Effective icons are recognizable at 48px (the smallest size users see in search results), use a single dominant visual element rather than multiple competing motifs, and avoid text (which is illegible at small sizes and triggers automatic rejection on Apple). Adaptive icons (Android) and SF Symbols-friendly composition (Apple) are platform-specific best practices.

Localization

Translating store listing metadata, screenshots, and (ideally) the in-app experience into additional languages. The single highest-ROI growth lever for most indie apps, because translated listings rank in search for the target language and convert at native rates. Google Play supports 77 listing languages, Apple supports 40. Localizing just title and short description into the top five non-English app markets (Spanish, Portuguese, German, French, Japanese) typically lifts installs 20–40%.

Bundle ID / Package Name
Apple: Bundle ID (e.g., com.theritzplaza.ionsleep) · Google: Package Name (same format)

The reverse-DNS unique identifier for an app. Permanent for the life of the app — cannot be changed after first publish on either store without creating a new app listing (losing all reviews, ratings, and installs). Choose carefully at first submission; conventional format is com.[company].[appname].

Indexed Keywords

The set of search terms an app can rank for. On Google Play, indexed keywords are extracted from the title, short description, and long description (and to a lesser degree, reviews and developer name). On Apple App Store, indexed keywords come from the title, subtitle, the dedicated 100-character keyword field, and the in-app purchase names — the long description is not indexed. The two stores require entirely different keyword strategies.

Custom Store Listing
Google Play feature · up to 50 per app

An alternate store listing (different short description, screenshots, etc.) shown to users from specific countries, install sources (e.g., a particular UTM-tagged campaign), or audience segments. Used to tailor messaging to acquisition channels without splintering the main listing. Apple's equivalent is Custom Product Pages, capped at 35 per app and assignable per ad campaign.

Android Vitals
Google Play technical-quality metrics

The technical-quality dashboard in Play Console covering crash rate, ANR (Application Not Responding) rate, slow rendering frames, slow startup time, excessive wakeups, and excessive battery use. Apps that exceed Vitals "bad behavior" thresholds (crash rate >1.09% of sessions in a 28-day window) get ranking and visibility penalties and a warning banner on the store listing. Apple has no direct equivalent dashboard but applies similar quality signals via App Store review.