Plain English
App Building Glossary
The words you'll encounter while building and shipping your app: TestFlight, EAS Build, Expo, app store screenshots, App Store Connect, and more, explained simply, no jargon, with enough detail to actually be useful.
- TestFlight
- TestFlight is Apple's official app for distributing beta builds of your iOS app to testers before you submit it to the App Store. You upload a build from App Store Connect, invite testers by email or a public link, and they install and run your real app on their own iPhones. TestFlight is how you catch crashes, confirm the paywall works, and get feedback before Apple's review sees it. Getting a build onto TestFlight and running it on a real device is one of the first milestones every new iOS builder should hit. Read more →
- EAS Build
- EAS Build is Expo Application Services' cloud build system - it compiles your React Native app into a real native iOS and Android binary in the cloud, with no Mac required. Instead of wrestling with Xcode and Android Studio locally, you run one command and EAS produces the signed builds you submit to the App Store and Google Play. EAS Build is the reason a solo builder on any computer can ship native apps to both stores. Pairing it with EAS Submit gives you an end-to-end pipeline from code to live listing. Read more →
- Expo
- Expo is a framework and set of tools built on React Native that lets you write one app in JavaScript and ship it as a real native app to both the Apple App Store and Google Play. It handles the hard native plumbing - build config, updates, common device APIs - so you focus on your app instead of platform setup. Paired with EAS for cloud builds and submissions, Expo is the stack that lets a non-native developer, or Claude Code writing on your behalf, produce a genuine native app for both stores from a single codebase. Read more →
- App Store Optimization (ASO)
- App Store Optimization (ASO) is the practice of improving where and how often your app appears in App Store and Google Play search - the app-store equivalent of SEO. It covers your app title, subtitle, keyword field, description, screenshots, and ratings, all tuned to the terms people actually search. Good ASO is the difference between an app that gets found and one that is buried among 5 million others. Because both stores are search engines, finding the keyword gaps big apps left open is one of the highest-leverage free skills a new builder can learn.
- App Store Screenshots
- App store screenshots are the images on your App Store and Google Play listing that show what your app looks like and does - the first and often only impression a browsing user gets before deciding to install. Well-made screenshots lead with your app's core value, use clear captions, and are sized correctly for each device. They are not deception; the app is what it is. They are the difference between a user scrolling past and a user tapping install. On a listing where the screenshots do most of the selling, getting them right is one of the highest-leverage skills a builder can build. Read more →
- Guideline 4.3
- Guideline 4.3 is Apple's spam-and-clone rule and the number-one reason first-time apps get rejected. It rejects apps that are too similar to something already in the store or that look like a reskinned template with a new logo. 'This app is just a duplicate of an existing app' on your first submission is a 4.3 rejection. It is not a dead end - the fix is always the same: build something genuinely distinct with real features and a real purpose. As a builder, understanding 4.3 before you start is how you avoid building straight into a rejection.
- Over-the-Air Updates
- Over-the-air (OTA) updates let you push certain changes to your app - JavaScript and asset fixes - directly to users' devices without submitting a whole new build to the stores for review. With Expo's update service you can fix a bug or tweak copy and have users get it on their next launch, instead of waiting days for another App Store review. OTA updates are a low-friction way to ship small fixes fast. The tradeoff is that native changes still require a full store submission, so OTA is for the layer your app logic lives in, not everything.
- RevenueCat
- RevenueCat is a service that sits on top of Apple's and Google's in-app purchase systems and manages your subscriptions from one place - products, receipts, entitlements, and revenue across both stores. Instead of writing fragile receipt-validation code for each platform, you ask RevenueCat one question: does this user have access? Wiring subscriptions through RevenueCat means real recurring payments work reliably on iOS and Android with far less code and fewer edge-case bugs. Knowing how to set up a RevenueCat paywall and test it before you submit is a core monetization skill.
- App Store Connect
- App Store Connect is Apple's web dashboard for managing your iOS apps - creating the app listing, uploading builds, defining in-app purchase products, filling in metadata and privacy answers, distributing TestFlight betas, and submitting for review. It is where everything about your app on Apple's side lives. Getting comfortable in App Store Connect - creating your app record early, setting up your subscription products, and answering the App Privacy questions honestly - is a required step on the path to a live iOS listing, and one the club walks through screen by screen. Read more →
- Google Play Console
- Google Play Console is Google's web dashboard for managing your Android apps - creating the store listing, uploading builds, setting up in-app products, filling in the Data safety form and content rating, running the required closed test, and promoting to production. It is the Android counterpart to App Store Connect. Getting set up in Play Console early - enrolling your developer account, starting the 14-day closed test, and completing the compliance forms - is a required step on the path to a live Google Play listing, and one where starting early saves you weeks of waiting.
- Closed Testing
- Closed testing is a limited-release track in Google Play Console where a controlled group of testers runs your app before it goes public. For new personal developer accounts, Google requires a closed test - at least 12 testers active for a continuous 14 days - before you can promote the app to production. It is the main early hurdle on Android, and it is time-based, so the smart move is to start it early. The hardest part for a solo builder, finding 12 real testers, is exactly what a community solves by becoming your tester pool.
- Code Signing
- Code signing is the cryptographic process that proves a build of your app really came from you and has not been tampered with - both Apple and Google require every app to be signed before it can be installed or submitted. It involves certificates and keys that used to be a major source of setup pain. The good news is that EAS Build can manage much of your signing for you in the cloud, so you get a properly signed build without hand-configuring certificates. Understanding that a valid signature is required, and letting EAS handle it, keeps signing from blocking your launch.
- App Idea Validation
- App idea validation is the process of proving people actually want your app before you build it - the research half of shipping. Validation channels include App Store and Google Play search volume, the reviews of competing apps, top-chart trends, and confirming a specific audience will download and pay. Good validation is a repeatable routine, not a hunch: you check search demand, read the complaints in existing apps, and confirm willingness to pay before you write a screen. Most of an app's success is decided at validation, because you save yourself when you pick the right idea, not when you build.
- Native App
- A native app is a real application installed on a phone from the App Store or Google Play that can use the device's hardware and runs like any other app - as opposed to a website or a web app opened in a browser. Building a native app used to require learning Swift or Kotlin, but with Expo and React Native you write one JavaScript codebase that compiles to genuine native iOS and Android apps. The term captures the whole goal of App Store Launch Club - describe it, build it, ship it - where the skill is turning a plain-English idea into a real native app on both stores without coding from scratch.
- Apple vs Google Play
- Apple vs Google Play is the comparison every builder weighs when launching: Apple's App Store has stricter human review and a higher-spending audience, while Google Play publishes faster but requires new personal accounts to pass a 14-day, 12-tester closed test first. Fees on both drop to 15 percent under the Small Business programs. The practical answer for most builders is not either-or: with Expo you build one codebase and submit to both stores from one pipeline. Matching your launch sequence to each store's requirements - starting Google's closed test early, submitting a clean build to Apple - is a core shipping skill.
- App Store Fees
- App store fees are the cuts Apple and Google take from in-app purchases and subscriptions sold through their stores. The standard rate is 30 percent, but both Apple's and Google's Small Business programs drop it to 15 percent for developers under the revenue threshold - so you keep 85 percent when enrolled. Fees matter because they come straight out of your revenue, and both stores require digital goods to go through their in-app purchase systems rather than an outside checkout. Enrolling in both Small Business programs and pricing with the 15 percent cut in mind is how you keep the most of every sale.
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Related: curriculum, guides, and the blog.