Babel CLI comes with [two executables](https://babeljs.io/docs/usage/cli/): `babel`, which compiles ES6 files into new ES5 files, and `babel-node`, which you can use to replace your call to the `node` binary and execute ES6 files directly on the fly. `babel-node` is great for development but it is heavy and not meant for production. In this chapter we are going to use `babel-node` to set up the development environment, and in the next one we'll use `babel` to build ES5 files for production.

If you try to run `yarn start` now, it should print the correct output, but Babel is not actually doing anything. That's because we didn't give it any information about which transformations we want to apply. The only reason it prints the right output is because Node natively understands ES6 without Babel's help. Some browsers or older versions of Node would not be so successful though!