COOPERATIVE LINUX, abbrieviated as coLinux, is a software that lets Microsoft Windows cooperate with the Linux kernel, to run both in parallel, on the same machine. Cooperative Linux utilizes the concept of a Cooperative Virtual Machine (CVM). In contrast to the traditional Virtual Machines(VMs), the CVM shares, the resources that already exist in the host OS. In traditional (host) VMs, resources are virtualized for every (guest) OS. The Cooperative Virtual Machine(CVM) gives both operating systems complete control of the host machine, while the traditional VM sets every guest OS in an unprivileged state to access the real machine.

The term cooperative is used to describe two entities working in parallel. In effect, Cooperative Linux turns the two different operating system kernels into two big *coroutines. Each kernel has its own complete CPU context and address space. Each kernel also decides when to give control back to its partner. However, while both kernels theoretically have full access to the real hardware, modern PC hardware is incompatibly designed to be controlled by two different operating systems at the same time. Therefore the host kernel is left in control of the real hardware, while the guest kernel contains special drivers that communicates with the host and provide various important devices to the guest OS. *program components that generalize subroutines to allow multiple entry points and suspending and resuming of execution at certain locations.