Quick ASOApp name (title)
The name shown for your app on the App Store, 2 to 30 characters. It is searchable and is the strongest text signal you write. See title and subtitle.
App Store Optimization (ASO)
The ongoing work of making an app easier to find in App Store search and more likely to be downloaded once it is found. The first half is keywords and metadata; the second is icon, screenshots and ratings.
Apple Ads
Apple's advertising platform, formerly called Apple Search Ads. It lets you pay to promote an app in places such as App Store search results. Paid placements are separate from organic ranking.
ASO audit
A review of an app's metadata and rankings that ends in a list of what to change: which phrases it already ranks for, which it is missing, and which words are wasted.
Autocomplete (search suggestions)
The list of phrases the App Store suggests as you type in the search box. It is a free signal of what people search for, though it also includes some app names.
Conversion rate
The share of people who saw your app, or opened its product page, who went on to download it. Icon, screenshots, ratings and the first lines of the description move it.
Custom product page
An alternative version of your product page, with its own screenshots, previews and text, made for a particular audience. Apple lets you choose keywords for which it appears in search results.
Downloads (installs)
The number of times people get your app. Apple lists downloads as part of the user behavior that feeds into search results.
Impressions
The number of times your app was shown to people in the App Store, for example in search results. App Store Connect reports them, with product page views and downloads.
Indexing
When Apple adds the words in your metadata to what it can match searches against. Apple says your primary and secondary categories are indexed, and that an app is searchable by app name and company name.
Keyword difficulty (competitiveness)
How hard it is to reach the top results for a phrase, usually judged from the strength of the apps already there. Quick ASO scores it from 0 to 100 using the rating volume of the top ten results.
Keyword field
A private, comma-separated list of search terms you enter in App Store Connect for each localization. Customers can't see it. Apple allows 100 characters (100 bytes in App Store Connect) with no spaces. See the keyword field guide.
Keyword popularity (search popularity)
How often a phrase is searched, relative to other phrases. Apple doesn't publish keyword search volume in App Store Connect, so tools estimate it; Quick ASO scores it from 5 to 100 using autocomplete.
Keyword ranking (search rank)
The position of your app in the search results for one phrase. Position 1 is the first result; where you rank differs for every phrase and every country.
Localization
A version of your listing for one language or region. Each localization has its own name, subtitle and keyword field, so it is a chance to reach more searches.
Long-tail keyword
A longer, more specific phrase that fewer people search for but that has fewer strong competitors, such as "secure photo vault with fingerprint lock". Very long suggestions are often other apps' names, so check that people really search them.
Metadata
The text and media that make up your listing: name, subtitle, keywords, description, promotional text, screenshots, previews and categories.
Primary category
The main category you choose for your app. Apple indexes it for search, together with the optional secondary category.
Product page
The App Store page for your app, with its icon, screenshots, description and ratings. Its job is conversion: turning a view into a download.
Product page optimization
Apple's built-in way to test alternative versions of your icon, screenshots and app previews against the original, using real App Store traffic.
Ratings and reviews
Star ratings and written reviews from customers. Apple says they influence how an app ranks in search and appear in the results, so they affect both ranking and conversion.
Storefront
The App Store of one country or region. Search results and ranks differ by storefront, so an app can rank first in one and not at all in another.
Subtitle
A summary of up to 30 characters shown under your app's name on the product page. It is searchable, and customers read it.
Text relevance
How well your title, subtitle, keywords and primary category match a search. Apple names it, with user behavior, as one of the two groups of signals behind search results.
Top Grossing chart
Apple's chart that ranks apps by the revenue they earn. Apple publishes the order but not the revenue, so any revenue figure for another app is an estimate.
User behavior
Apple's name for the signals that come from how people use the App Store, such as downloads and ratings and reviews. It works alongside text relevance.
Want the longer version?
The complete ASO guide explains how these pieces fit together, and the guides go deep on one question at a time.