Communication system, server apparatus, and display control method

According to one embodiment, a server apparatus includes a connection controller which selectively executes first processing to execute the communication connections among the several data terminals, respectively, and second processing to make the several data terminals, respectively, to communication-connect to the conference processing unit, a processor which executes a first screen display mode to individually display a plurality of screens, related to each of the several data terminals, and executes a second screen display mode to display screens, in which a plurality of screens related to each of the several data terminals are synthesized by the conference processing unit, based on the prescribed conditions, and a switching controller which selectively executes switching from the first screen display mode to the second screen display mode, or from the second screen display mode to the first screen display mode, and maintaining a screen display mode before switching, based on the prescribed conditions.