Next.js includes the `next/babel` preset to your app, which includes everything needed to compile React applications and server-side code. But if you want to extend the default Babel configs, it's also possible.
To start, you only need to define a `.babelrc` file (or `babel.config.js`) at the top of your app. If such a file is found, it will be considered as the _source of truth_, and therefore it needs to define what Next.js needs as well, which is the `next/babel` preset.
You can [take a look at this file](https://github.com/vercel/next.js/blob/canary/packages/next/build/babel/preset.ts) to learn about the presets included by `next/babel`.