OpenVZ is a container-based virtualization for Linux. OpenVZ creates multiple secure, isolated Linux containers (otherwise known as VEs or VPSs) on a single physical server enabling better server utilization and ensuring that applications do not conflict. Each container performs and executes exactly like a stand-alone server; a container can be rebooted independently and have root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files.
OpenVZ is free open source software, available under GNU GPL.
OpenVZ is the basis of Virtuozzo, a virtualization solution offered by Virtuozzo company. Virtuozzo is optimized for hosters and offers hypervisor (VMs in addition to containers), distributed cloud storage, dedicated support, management tools, and easy installation.