The Create-React-App tool hides all of the Babel and Webpack configuration by default. The only dependency you have in your app is the `react-scripts` package.

This drastically simplifies things for your app, and means you can get the latest build system updates with a single update command whenever a new version of `react-scripts` comes out. However, it also means that if you _do_ need to modify the configuration in some way, it's normally inaccessible.

CRA includes a one-time `npm run eject` command that copies over all of the actual dependencies and config files into your project. "Ejecting" means you're taking ownership of those config files, and also means you lose the ability to easily upgrade with a single command.