[get started with React](/react/docs/getting-started.html). The starter kit includes React, the in-browser JSX transformer, and some simple example apps.
We provide two versions of React: an uncompressed version for development and a minified version for production. The development version includes extra warnings about common mistakes, whereas the production version includes extra performance optimizations and strips all error messages.
If you're using an npm-compatible packaging system like browserify or webpack, you can use the `react` package. After installing it using `npm install react` or adding `react` to `package.json`, you can use React:
**Note:** by default, React will be in development mode. To use React in production mode, set the environment variable `NODE_ENV` to `production`. A minifier that performs dead-code elimination such as [UglifyJS](https://github.com/mishoo/UglifyJS2) is recommended to completely remove the extra code present in development mode.