The Facebook Link Shim helps protect the identity of the user clicking through on a link to the destination landing page.

The Facebook Link Shim can be identified in Google Analytics and Statistical Reporting as l.facebook.com / referral and lm.facebook.com / referral (mobile).

It helps Protect Privacy and Identity of the end user.  It also strips valuable marketing and referral data from statistical reporting.

NOTE:  It should be mentioned and clarified for many people using Google Analytics and many other statistical reporting tools that before introducing the Facebook Link Shim being identified as l.facebook.com / referral and lm.facebook.com / referral your statistics may have classified this traffic under Unknown or No Referrer or No Referral Data, Etc.

For more on the Facebook Link Shim Click Here>>