Expo
A toolchain and platform for React Native: managed workflow, dev client, modules, and services that speed up building and shipping mobile apps.
What it is
Expo provides a development environment, libraries for common native features, build profiles, and integrations (including EAS) so you spend less time on raw native project plumbing.
Why it matters
It standardizes RN project setup, shortens the path to device testing, and aligns teams on a supported module ecosystem and update workflows.
When to use it
Default choice for many new RN apps unless you have a clear need for fully custom native code from day one. You can still eject or use custom dev clients when requirements grow.
How it fits in the stack
Expo wraps React Native: same RN core concepts, with opinions about tooling, OTA updates (where allowed), and builds via EAS. The app remains a React Native app under the hood.
Common confusion
Expo is not a separate mobile framework from React Native. It is tooling and services on top of RN. Expo Go is for development convenience, not a substitute for store-ready binaries and signing.