I am wondering there are many sites which is opened to user directly i.e. open Browser and type website name and hit enter. Like: Google.com (we usually open it directly). If I have a adSense ads to such sites, what I may find difference in earning ? Google won't find any referral to such site, so will they pay me less or what will be the effect of it ! Sorry to make mistake in Tittle: What if referral to Site is NULL
If someone typed in your site in a search engine to get to it then you would earn more than you would from referral traffic.