The <code>--save</code> or <code>-S</code> flag adds the package to the <code>"dependencies"</code> list in your <code>package.json</code> file.
The <code>"dependencies"</code> list contains all the packages needed to run your application.

The `--save` or `-S` flag adds the package to the `"dependencies"` list in your `package.json` file.

The `"dependencies"` list contains all the packages needed to run your application.

It tells NPM to install to the <code>"dependencies"</code> list in the <code>package.json</code> file.
As of NPM version <code>5</code>, packages are installed to <code>"dependencies"</code> by default. Therefore, the <code>--save</code> flag is no longer needed. There are still other save options that are listed in the NPM documentation.

It tells NPM to install to the `"dependencies"` list in the `package.json` file.

**As of NPM version `5`, packages are installed to `"dependencies"` by default. Therefore, the `--save` flag is no longer needed. There are still other save options that are listed in the NPM documentation**.

I've seen the <code>npm install --save</code> command used in several different places, but can't figure out what the <code>--save</code> option does.

What does the --save option do when using npm install?