A host-based virtual machine is an instance of a desktop operating system that runs on a centralized server. Access and control is provided to the user by a client device connected over a network. Multiple host-based virtual machines can run on a single server.
With a host-based virtual machine, data is contained on the server, server resources can be allocated to users as needed, users can work from a variety of clients in different locations, and all of the virtual machines can be managed centrally. However, the client device must always be connected to the server in order to access the virtual machine, and when one single server is compromised many users can be affected.
Host-based virtual machines are conceptually similar to Windows Terminal Server environments, except host-based virtual machines have one virtual machine for each user, whereas Terminal Server has many users sharing the same instance of Windows.
Host-based virtual machine is another term for virtual desktop infrastructure (VDI), though usage of the term VDI has grown to include client-based virtual machines as well as host-based virtual machines.