Can someone explain what it is in plain words? I got some installation which required libXinerama. Eventually I got it working but I would like to know what it does and how it interacts with the rest of the system.
Thank you,
Xinerama is an X11 extension which provides support for extending a desktop across multiple displays. (The name is a pun on Cinerama, a widescreen movie format which used multiple projectors.)
The Xinerama extension is largely obsolete nowadays -- it has been replaced by the RandR extension, which provides the same functionality on a more flexible basis. Some older programs still use the Xinerama interface, though, and the RandR extension provides a compatibility interface for these programs.
libXinerama is the library which interfaces with this extension.