Relationship between Wikimedia and Facebook, Inc.
Use of Facebook products on Wikimedia
Facebook social network
Some Wikimedia organizations maintain Facebook pages.
Certain Wikimedia projects have policies restricting linking to Facebook.[1]
HHVM
In November 2014, Facebook's open-source HHVM PHP interpreter tool was deployed on Wikimedia servers, in order to decrease loading time on Wikimedia projects. In September 2017, the Wikimedia Foundation adopted a plan to drop HHVM. (See phab:T176370.)
Donations
In December 2018, Facebook donated $1 million to the Wikimedia Endowment.[2]