Xen

Xen is best known as the Xen Project hypervisor, a type-1 virtualization platform that runs directly on hardware and manages multiple guest operating systems. It originated at the University of Cambridge and has been developed as an open-source project under the Xen Project umbrella. It supports paravirtualization and hardware-assisted virtualization (PV, HVM) and uses domains such as Dom0 to manage DomU guests. It has been widely used in cloud computing, including historical use by public clouds such as Amazon EC2 and by various Linux distributions.

In video games, Xen is the extradimensional planet or realm in Valve’s Half-Life series. The Xen dimension is accessed via portals and features distinct flora, fauna, and physics that differ from the human world. It serves as a key setting in the series, appearing in the original game and in subsequent titles and expansions.

The prefix xen- derives from the Greek xenos, meaning foreign or strange. It appears in numerous terms across science, medicine, and social science, such as xenophobia, xenograft, xenotransplantation, and xenobiology. In popular culture, Xen is often used as a generic label for aliens or other foreign entities. The term thus spans technology, entertainment, and language, reflecting its roots in concepts of otherness and difference.