VPS refers to a Virtual Private Server; this is a method of partitioning a single physical server computer to provide services to several users concurrently.
The virtual machines created function as separate physical computers which allow users to modify their server environment to their needs.
This partitioning creates an entirely separate server environment for each user with the privacy of a detached server unit.
A VPS server is most commonly used for internet hosting services; the multiple logical servers created allow organizations to provide access to content via the internet.
VPS hosting is possible based on the nature of resource usage.
Resources are usually requested in bursts; high priority requests for resource control limited to a short period of time combined with high periods of network inactivity.
This makes it possible to develop software that mathematically models resource allocation in a manner that serves each user.
This software is termed the hypervisor; it controls the creation, modification, and deletion of virtual machines within the server environment.
It does this by translating the underlying physical and network infrastructure into a virtualized environment.
This virtual environment is then structured to represent the actual resources that each virtual machine will have access to and usage of.
Thus, the virtual machine only sees the resources it has been allocated.
VPS hosting allows a virtual machine to install and run its own operating system layered onto the existing basic software infrastructure.
This enables you to undertake tasks such as software upgrades and reboot without affecting other users.
The hosting service can be either managed or unmanaged.
In managed hosting, the service provider undertakes administration of all the virtual servers created from a centralized control panel.
In unmanaged hosting, you are left in charge of the maintenance and administration of their server.
The service provided can be either metered or unmetered depending on server bandwidth allocation.
Where the end user is not limited on usage of bandwidth this is termed unmetered.
In metered hosting, the bandwidth is allocated in multiples of ten megabits per second.
The VPS server environment you are provided with can be fully virtualized, Para virtualized or a hybrid environment.
In a fully virtualized system, the virtual machines are unaware that their interaction with the system is controlled through a hypervisor as they are unaware of the underlying physical structure.
In Para virtualized systems, the virtual machine, while aware of the existence of the hypervisor, is allowed interaction with the host resources directly.
A hybrid system is used where modification of the main operating system is impossible.