"The AdSense code" is the name of the HTML snippet you put on your site to get Auto ads and a range of other AdSense features. If you've been using AdSense for a while, you might know this code by its old name: "Auto ad code". To get the most out of AdSense, place the AdSense code on every page across your site.
Here's an example of the Auto ad code:
<script async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=ca-pub-1234567890123456" crossorigin="anonymous"</script>
You can use the AdSense code to get Auto ads, but Auto ads now works through any AdSense ad unit code.
Note: This behavior may not work correctly for ad unit code that is used dynamically, through an ad server, or used via a host partner website.