A logical partition of a computer’s resources, such as processors, memory and storage, that is virtualized as a separate computer instance. Each partition can host its own operating system and applications. Multiple LPARs can run on the same machine. Typically, partitions are used for different functions, such as for test and production environments. A partition communicates with another partition as if the other partition is on a separate machine. LPARs are compatible with multiple operating system types, including z/OS, i5/OS, AIX, and Linux. IBM z/OS systems operate exclusively in LPAR mode.