OS template
An OS template is basically a set of packages from some Linux distribution used to populate a VE. With OpenVZ, different distributions can co-exist on the same hardware box, so multiple OS templates are available.
An OS template consists of system programs, libraries, and scripts needed to boot up and run the system (VE), as well as some very basic applications and utilities. Applications like a compiler and an SQL server are usually not included into an OS template.