Site Authorization is an optional feature in Google AdSense that allows you to identify only specific sites that you wish to display your ads on.
If you are particularly concerned about malicious use of your ad code by others, you may wish to use this feature as a precaution.
If you are not, you need not exercise this option!
To access this setting, open your AdSense account > Account settings > Access and Authorization > Allow any site to display ads for your account. I am assuming that you are using the new AdSense interface!
I had exercised this option quite a few years back to be on the safe side, but when I went today to check it out, I was surprised to see a lot of sites being mentioned, many of them well-known.
Why and how – I have no idea! But hey, I checked each of them and decided to Authorize some of these sites to display my ads!
If a URL displaying your AdSense ad code is not on your list of authorized sites, ads will still show on that URL and impressions and clicks will be recorded. However, advertisers will not be charged, and you will not receive any earnings for that site.
So please enable this feature with caution to avoid missing out on valid revenue!
If you have not yet exercised this option, you will have to first opt for this option. You will then get to see after 48 hours, who if any, are displaying your ads.
If you want, you can even authorize select websites who you trust, to display your ads.