> This document is for Next.js versions 9.4 and up. If you’re using an older version of Next.js, upgrade or refer to [Environment Variables in next.config.js](/docs/api-reference/next.config.js/environment-variables.md).
This loads `process.env.DB_HOST`, `process.env.DB_USER`, and `process.env.DB_PASS` into the Node.js environment automatically allowing you to use them in [Next.js data fetching methods](/docs/basic-features/data-fetching) and [API routes](/docs/api-routes/introduction).
By default all environment variables loaded through `.env.local` are only available in the Node.js environment, meaning they won't be exposed to the browser.
This loads `process.env.NEXT_PUBLIC_ANALYTICS_ID` into the Node.js environment automatically. Allowing you to use it anywhere in your code. The value will be inlined into JavaScript sent to the browser because of the `NEXT_PUBLIC_` prefix.
In general only one `.env.local` file is needed. However, sometimes you might want to add some defaults for the `development` (`next dev`) or `production` (`next start`) environment.
Next.js allows you to set defaults in `.env` (all environments), `.env.development` (development environment), and `.env.production` (production environment).
> **Note**: `.env`, `.env.development`, and `.env.production` files should be included in your repository as they define defaults. **`.env*.local` should be added to `.gitignore`**, as those files are intended to be ignored. `.env.local` is where secrets can be stored.
When deploying on [Vercel](https://vercel.com) you can configure secrets in the [Environment Variables](https://vercel.com/docs/v2/build-step#environment-variables) section of the project in the Vercel dashboard.
If you've configured [Development Environment Variables](https://vercel.com/docs/v2/build-step#development-environment-variables) you can pull them into a `.env.local` for usage on your local machine using the following command:
Apart from `development` and `production` environments, there is a 3rd option available: `test`. In the same way you can set defaults for development or production environments, you can do the same with `.env.test` file for testing environment (though this one is not so common as the previous two).
This one is useful when running tests with tools like `jest` or `cypress` where you need to set specific environment vars only for testing purposes. Test default values will be loaded if `NODE_ENV` is set to `test`, though you usually don't need to do this manually as testing tools will address it for you.
There is a small difference between `test` environment, and both `development` and `production` that you need to bear in mind: `.env.local` won't be loaded, as you expect tests to produce the same results for everyone. This way every test execution will use same env defaults across different executions by ignoring your `.env.local` (which is intended to override the default set).
> **Note**: similar to Default Environment Variables, `.env.test` file should be included in your repository, but `.env.test.local` shouldn't, as `.env*.local` are intended to be ignored through `.gitignore`.