What is the underscore "_" in JavaScript? : <p>I'm doing a redux tutorial, and I saw a call like this:</p>

<pre><code>this._render();
</code></pre>

<p>and it's defined elsewhere as:</p>

<pre><code>_render() {
    ....
} 
</code></pre>

<p>What is the underscore "_"? Why is it used?</p>
