App store optimisation (ASO) is the work of improving an app’s listing in Apple’s App Store and Google Play so that it ranks higher when people search the stores and so that more of the people who see it go on to install. It is to app stores what SEO is to Google: part visibility, part persuasion.
How app store optimisation works
Both stores run their own search engines. They match a user’s search to the words in an app’s listing, then rank matching apps using signals such as download volume and momentum, ratings, reviews and how often people who see the listing install it.
The two stores read different fields. On Apple’s App Store, the app name (up to 30 characters), the subtitle (30 characters) and a hidden keyword field (100 characters) carry most of the search weight; the long description is not used for ranking. On Google Play, the title (30 characters), short description (80 characters) and full description (up to 4,000 characters) are all read, so Play behaves more like web search, and natural use of key phrases in the description matters.
The second half is conversion. Your icon, screenshots, preview video, rating and first lines of description decide whether a searcher installs. Both stores let you test variations: product page optimisation on Apple and store listing experiments on Google Play. They also let you build custom listings for different audiences or campaigns.
Why it matters
For a UK business with an app, such as a gym chain, a takeaway, an estate agent or a fintech, store search is often where most organic installs come from. Every install that arrives through search is one you do not pay for.
ASO also affects paid acquisition. A Google app campaign sends people to your Play or App Store listing, so a weak listing with a low conversion rate raises the cost of every install you buy. Improving the listing lowers that cost without changing the ads.
Localisation is easy to miss. Apple lets you add an English (UK) localisation in App Store Connect, separate from US English, and Google Play supports an en-GB listing. If UK users search for “trainers” or “football scores” and your listing says “sneakers” and “soccer”, you lose relevance and look out of place.
Common mistakes
- Repeating the same word across the Apple name, subtitle and keyword field, which wastes characters because Apple combines them.
- Leaving the listing unchanged for years while competitors test new screenshots and wording.
- Screenshots that show settings menus rather than the benefit a user gets.
- Ignoring ratings: asking for a review at a frustrating moment, or never asking at all.
- Putting competitor brand names in metadata, which breaches store guidelines and can get an update rejected.
- Only supporting US English, so UK spelling and terms never match.
How to act on it
Start with keyword research for the stores, not the web: list the words UK users type to find apps like yours, check the apps that rank for them, and pick terms you can realistically compete for. Rewrite your title, subtitle or short description and keyword field around them, using UK spelling.
Then work on conversion. Redesign the first three screenshots to show outcomes, test them with the stores’ experiment tools, and ask for ratings after a user completes something satisfying. Reply to reviews, especially critical ones. If you also run paid campaigns, the listing improvements make the ads cheaper; I cover that side in my Google Ads app campaign management.