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ASO Glossary

Plain-language definitions of the App Store Optimization terms that actually move installs — written by the team that does this for funded app startups every day. 90 terms and growing.

Foundations

App Store Optimization (ASO): Is the practice of improving an app's visibility and conversion in app store search and browse so it earns more organic installs without paying per download.

App Store mechanics

Cross-Localization: Is the App Store behavior where a single country storefront indexes keywords from more than one localization — letting you rank for extra terms by filling secondary localizations users in that country never see.
Localization: Is adapting an app's store listing — metadata, screenshots, and keywords — to a specific language and market so it ranks and converts in that audience's own language.
Storefront: Is a single country or region's version of the App Store, with its own charts, search rankings, featuring, and set of indexed localizations.
Primary Localization: Is the default language of a storefront — the metadata most users in that country see, and the first localization the App Store indexes for keyword search there.
Secondary Localization: Is an additional localization whose keyword field the App Store also indexes in a storefront — giving you extra keyword coverage that most users in that country never see.
App Category: Is the store classification you assign your app, which sets the charts and browse lists it competes in and influences which searches it surfaces for.
Product Page: Is an app's page on the App Store — icon, name, subtitle, screenshots, previews, ratings, and description — and the screen where a shopper decides whether to install.

Metadata

Keyword Field: Is the App Store's hidden 100-character metadata field where you list comma-separated keywords that count toward search ranking but are never shown to users.
App Title (App Name): Is the most heavily weighted ranking field on both stores — up to 30 characters on the App Store — where your brand name and single most valuable keyword belong.
Subtitle: Is the App Store's 30-character line beneath the app name — the second-strongest ranking field and a key conversion hook on the product page.
Promotional Text: Is a 170-character App Store field above the description that you can update anytime without a new app release — but it does not affect keyword ranking.
App Description: Is the long-form text on a store listing — on Google Play it directly affects keyword ranking, while on the App Store it is conversion-only and not indexed for search.
Metadata Character Limits: Are the fixed maximum lengths Apple and Google enforce on each listing field — the limit is enforced when you enter text, so over-limit copy won't save; truncation happens only on display.
Metadata: Is the collection of text fields — app name, subtitle, keyword field, description and more — that tell a store what your app is and which searches it should appear for.
Stop Words: Are filler words like "the" and "to" — and, in ASO usage, broad terms like "app" — that add no value in the App Store keyword field and waste its characters.
Keyword Density: Measures how often a keyword appears relative to the total words in a text field — relevant to Google Play's indexed description, but not to the App Store description, which isn't indexed.
What's New (Release Notes): Is the App Store's per-version update text, up to 4,000 characters, and its Google Play counterpart, release notes, capped at 500 characters per language — telling users what changed in each update.

Discovery & ranking

App Store Search Algorithm: Is the system that ranks apps for a search query based on keyword relevance in metadata combined with performance signals like downloads, conversion, and ratings.
Ranking Factors: Are the inputs an app store uses to order search and chart results — split between on-metadata relevance signals and off-metadata performance signals.
Keyword Difficulty: Is a score estimating how hard it is to rank on the first page for a keyword, based on the strength and competition of the apps already ranking for it.
Search Volume (Popularity Score): Is an estimate of how often users search a keyword — Apple expresses it as a 5–100 popularity score, and it tells you the traffic a top ranking could deliver.
Long-Tail Keyword: Is a longer, more specific multi-word search phrase with lower volume but higher intent and lower competition — often the fastest path to first-page rankings for a new app.
Branded Keyword: Is a search term containing a brand or app name — either your own (protecting it) or a competitor's (bidding or ranking against it).
Keyword Stuffing: Is overloading metadata with repeated or irrelevant keywords in a way that reads unnaturally, wastes ranking weight, and can trigger store rejection or hurt conversion.
Keyword Rank: Is your app's position in the search results for a specific keyword in a specific storefront — the core metric ASO is judged by.
Browse vs. Search: Are the two organic discovery paths in an app store — search (users typing a query) and browse (charts, categories, and editorial featuring) — which reward different optimizations.
Category Ranking: Is your app's position within its App Store or Google Play category chart, driven mainly by download velocity and a strong browse-discovery surface.
Install Velocity: Is the rate at which an app gains downloads over a short window — a momentum signal the store algorithms read as evidence that an app deserves higher ranking.
Search Suggestions (Autocomplete): Are the queries an app store proposes as a user types in the search bar, ordered roughly by popularity — a free, real-time read on what people actually search for.
Keyword Indexing: Is whether a store has registered your app as eligible to appear for a given term — if a keyword isn't indexed, you can't rank for it no matter how relevant you are.
Top Charts: Are the ranked lists of the most-downloaded apps by category and country, a high-traffic browse surface driven mainly by recent install velocity.
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.
Competitor Keyword Analysis: Is the practice of studying which keywords rival apps rank for to find high-value terms you're missing — the basis of a keyword gap analysis.
Keyword Research: Is the end-to-end process of finding, scoring and prioritizing the search terms an app should target, then placing each one in the metadata field where it can rank best.
Keyword Relevance: Is how closely a search term matches what an app actually does — a core input to store search ranking, and the reason an off-topic ranking rarely turns into installs.
Search Intent: Is the goal behind a store search — finding a specific app, comparing options in a category, or solving a particular problem — and it shapes which listing and message will convert.
Generic Keyword: Is a non-branded search term that describes a category, feature or task — such as "photo editor" or "budget planner" — rather than naming a specific app or company.
Keyword Combinations: Are the multi-word searches an App Store listing can appear for by combining words from its app name, subtitle and keyword field — so each word needs to appear only once.
Seasonal Keywords: Are search terms whose demand peaks around predictable dates — New Year fitness, holiday gifting, back-to-school — making them valuable for weeks and wasted space the rest of the year.

Metrics

Impressions: Count how many times your app listing or icon was shown to users across search, browse, and referrals — the top of the ASO funnel before taps and installs.
Organic Installs: Are app downloads that come from unpaid discovery — search, charts, browse, featuring, and referrals — rather than from paid advertising.
Tap-Through Rate (TTR): Is the share of people who, after seeing your app in search or browse results, tap through to open its product page — the App Store's version of click-through rate.
Retention Rate: Is the percentage of users still active a set number of days after install — a quality signal both app stores increasingly weigh when deciding how to rank an app.
Cost Per Install (CPI): Is the average amount you pay to acquire one install through paid channels — the benchmark organic ASO is measured against.
Product Page Views: Are the number of times users open your app's full store listing — the middle of the conversion funnel, between impressions and installs.
Visibility Score: Is a composite metric calculated by third-party ASO tools, typically weighting an app's keyword rankings by each term's search popularity — not an official Apple or Google metric.
Return on Ad Spend (ROAS): Measures the revenue generated by advertising divided by what that advertising cost, usually over a fixed cohort window such as the first 7 or 30 days after install.
Lifetime Value (LTV): Is the total revenue an app expects to earn from a user over the whole relationship, and it caps what a team can afford to pay to acquire that user.
Source Type (App Store Connect): Is the App Store Connect Analytics dimension recording where a user came from before viewing or downloading an app, such as App Store Search, App Store Browse or App Referrer.
First-Time Downloads: Is the App Store Connect Analytics metric counting people who download an app to their device for the first time; together with Redownloads, it makes up Total Downloads.

Conversion

Conversion Rate (CVR): Is the share of users who install your app after viewing its listing — the single metric that turns visibility into installs and feeds back into ranking.
Screenshots: Are the listing's primary conversion asset — the visual story of your app that shoppers scan in seconds and that does most of the work of earning an install.
App Preview (Video): Is the short autoplaying video on a store listing that demonstrates the app in motion — a strong conversion lever when it shows real value in the first few seconds.
App Icon: Is the small square mark that represents your app everywhere it appears — the first impression in search and browse, and a meaningful conversion and tap-through driver.
Ratings & Reviews: Are the star score and written feedback on your listing — a top conversion driver and a ranking signal, where both the average and the volume and recency matter.
Conversion Funnel: Is the path a user takes from seeing your app to installing it — impression, to product-page view, to download — where each step has its own drop-off to diagnose and fix.
A/B Testing: Is running two or more versions of a store-listing element against live traffic to measure which converts better — replacing opinion with data.
Rating Reset: Is an App Store Connect option that clears an app's summary star rating when a new version is released, letting the average rebuild from new ratings while written reviews stay visible.
In-App Rating Prompt: Is the system dialog that asks users to rate an app without leaving it — StoreKit's RequestReviewAction on Apple platforms and the In-App Review API on Google Play.
Developer Response: Is a public reply a developer posts to a user review through App Store Connect or Google Play Console, shown with the review on the store and notifying the reviewer.

Apple features

Product Page Optimization (PPO): Is Apple's native A/B testing feature that lets you test up to three variant treatments of your icon, screenshots, or app preview against the default and measure conversion.
Custom Product Pages (CPP): Are up to 70 additional versions of an app's App Store product page, each with its own screenshots, app previews and promotional text, built to match a specific audience, campaign or search.
In-App Events: Are timely, time-limited happenings inside your app — like a tournament, premiere, or challenge — that Apple lets you surface as discoverable event cards across the App Store.
Today Tab: Is the App Store's editorial home screen, where Apple's team features apps through stories and curated lists — an earned placement that drives large, ranking-boosting install spikes.
App Store Connect: Is Apple's suite of tools for submitting and managing apps on the App Store — per-localization metadata, pricing and releases, analytics, and responses to ratings and reviews.
App Store Tags: Are short descriptive labels Apple assigns to apps using large language models and human review, shown in US App Store search results and on product pages to aid discovery.
Promoted In-App Purchases: Are in-app purchases and subscriptions showcased on an app's App Store product page — up to 20 at a time — that can also appear in search results and editorial features.
Pre-Orders (App Store): Are an App Store option that publishes an app's product page before release, so people can order it in advance and have it download automatically to their device on launch day.
App Store Featuring: Is editorial placement chosen by Apple's App Store editors — Today tab stories, App of the Day, and themed collections — that can send a concentrated burst of browse traffic.
App Store Review Guidelines: Are Apple's rules that every app and update submitted to the App Store is reviewed against; section 2.3, Accurate Metadata, governs names, keywords, screenshots, and descriptions.
AdAttributionKit: Is Apple's privacy-preserving framework that lets registered ad networks, now including Apple Ads, attribute installs and re-engagements to ads through signed, delayed postbacks that carry no user-level data.

Paid acquisition

Apple Search Ads (ASA): Is Apple's paid search advertising platform that places sponsored app results at the top of App Store search — a paid channel that complements organic ASO.
Google App Campaigns: Are Google Ads' automated campaign type for promoting Android and iOS apps, building ads from supplied assets and serving them across Search, Google Play, YouTube, Discover and the Display Network.
Organic Uplift: Refers to the extra organic installs an app gains as an indirect result of paid acquisition, often called the halo effect, estimated through experiments rather than read from any store report.
Cost Per Tap (CPT): Is what an advertiser pays each time someone taps an Apple Ads Advanced ad, with the max CPT bid setting a ceiling rather than the price actually paid.
Search Match: Is an Apple Ads feature that automatically matches search results ads to relevant App Store queries using the app's metadata and data on similar apps, so advertisers needn't list every keyword.
Match Types (Exact vs. Broad): Are the two Apple Ads keyword settings, broad and exact, that decide how closely an App Store search must resemble a bidded keyword before the ad can show.
Negative Keywords: Are terms added to an Apple Ads search results campaign or ad group that stop the ad from showing for matching searches, cutting wasted spend and campaign overlap.
Apple Ads Placements: Are the four App Store positions where Apple Ads Advanced promotes apps (search results, the Search tab, the Today tab and product pages), of which only search results use keywords.

Google Play features

Custom Store Listings (Google Play): Are Google Play's audience-targeted listing variants that show different metadata and creative to specific countries, install states, pre-registration users, or ad campaigns.
Store Listing Experiments (Google Play): Are Google Play's built-in A/B testing tool for comparing listing variants — icon, screenshots, text, and more — against the current default to find what converts best.
Short Description (Google Play): Is the 80-character summary line on a Google Play listing: the first text users see on the app's detail page, and Play's closest equivalent to the App Store subtitle.
Feature Graphic (Google Play): Is the required 1024×500-pixel banner on a Google Play listing, used as the cover image for the preview video and in large-format collections across the store, including ads.
Android Vitals: Is Google Play's set of technical-quality metrics, led by user-perceived crash and ANR rates, whose bad-behavior thresholds can cost an app visibility when exceeded.
Google Play Console: Is Google's web dashboard for publishing and managing apps on Google Play, where store listings, experiments, acquisition reports, reviews and Android vitals all live.
Promotional Content (Google Play): Is Google Play's self-service tool, formerly called LiveOps, for promoting time-bound events, offers and major updates as cards on the store listing and across other Play surfaces.
Pre-Registration (Google Play): Is Google Play's pre-launch sign-up: users register for an upcoming app or game on its store listing, then get notified on launch day, with eligible devices installing it automatically.
Editors' Choice (Google Play): Is the label Google Play's editorial team uses to highlight what it deems the very best apps and games for a given topic, an editorial judgment that ad spend cannot buy.
Google Play Metadata Policy: Is the section of Google Play's Developer Program Policies governing store listing text and graphics, banning misleading, irrelevant, excessive or promotional metadata such as ranking claims and keyword repetition.

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