I set up my website so that I'm tracking the $_SERVER['HTTP_REFERER']
of every page visit. I'm also using Google Analytics. What's confusing me is that I'm seeing discrepancies. For example, GA shows that someone was referred to my site from m.facebook.com, but my list of referrals captured through PHP does not show that. Conversely, with my PHP I've seen some referrals from Bing such as http://www.bing.com/search?q=some+search and yet these don't align with what GA shows.
Can someone help me make sense of this? What are the differences in how the referral is calculated in each of these instances?