AdSense is the Ad Network of Google.
It's intended to be simple. If you want more control, you need to use the AdManager.
The adsense script is pagead2.googlesyndication.com/pagead/js/adsbygoogle.js that is loaded in a header.
<head>
<script async="" src="//pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
</head>
Adding an ad unit ask two piece of code:
<ins class="adsbygoogle"
style="display:block"
data-ad-client="ca-pub-9530166455702489"
data-ad-slot="9424922515"
data-ad-format="auto"
data-full-width-responsive="true"></ins>
<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>