Richard Williamson (plaintiff) owned a patent disclosing a method and systems for creating a “virtual classroom environment,” comprised of computers and a distributed learning server used for facilitating communication among participants. Specifically, Claim 8 of the patent described a “distributed learning control module” for receiving, transmitting, and relaying communications and coordinating system operations on a special purpose computer. Williamson sued Citrix Online, LLC (Citrix) (defendant) for infringement. Citrix contended the patent was indefinite under 35 U.S.C. §112. The district court determined that the term “distributed learning control module” was governed by § 112, paragraph 6, and found, among other things, that Claim 8 and its dependent claims were invalid. Williamson appealed.