In the past few months we have noticed a couple of new Facebook referral mediums popping up in our analytics data generating a not insignificant portion of total traffic. Aside from the standard facebook.com and m.facebook.com sources, l.facebook.com and lm.facebook.com have joined the family. It seems that aside from our clients, many other agencies using analytics were similarly puzzled by what exactly these new “l” based sources were.
Upon further research we believe that these new classes have been introduced by Facebook to protect user identity when accessing potentially malicious sites through what is known as the link shim. The danger being that full Facebook URLs sometimes containing a user’s full name could be read, compromising their security and anonymity.
In the past, the link shim prevented website owners from knowing that such traffic was from Facebook. As a result of the recent link shim improvement, we can have a more accurate representation of total Facebook referral traffic through the l.facebook (desktop/tablet) and lm.facebook (mobile) sources appearing in our google analytics data.
Ultimately this improved transparency allows us to make more informed decisions about how marketing budget is allocated and its corresponding return on investment.