Ad - AdSense

About

AdSense is the Ad Network of Google.

It's intended to be simple. If you want more control, you need to use the AdManager.

Articles Related

Script

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:

the ins insertion element

<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>

And a push script

<script>
(adsbygoogle = window.adsbygoogle || []).push({});
</script>

Why the push ?

When adsbygoogle.js has not yet loaded, then adsbygoogle.push({}) makes an array one element longer
When adsbygoogle.js loads, it iterates through the array, processing one ad slot for each entry.

Glossary

An AdUnit represents an ad location on one or more pages.