'The AdSense code' is the name of the HTML snippet that 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 data-ad-client="ca-pub-1234567890123456" async src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js"></script>
You can use the AdSense code to get Auto ads, but Auto ads now works through any AdSense ad unit code.
Note: This behaviour may not work correctly for ad unit code that's used dynamically, through an ad server or used via a host partner website.