What do the --save flags do with npm install
<p>I see instructions to install a package with either</p>

<pre><code>npm install &lt;package_name&gt;
</code></pre>

<p>or</p>

<pre><code>npm install &lt;package_name&gt; --save
</code></pre>

<p>or</p>

<pre><code>npm install &lt;package_name&gt; --save-dev
</code></pre>

<p>What is the difference between these options?</p>