What is a VPS?
A VPS is a virtual private service.
The VPS runs on a dedicated server, sometimes called a “VPS node”. The VPS node runs virtualization software, which allows the VPS to run, and an easy way I use to explain is it’s like a VPS node is a large pizza and you order “slices” of resources from that pizza.
VPS node hardware can be anything from a low end Intel Core2Quad (the Q9xx series isn’t that shabby) to Intel Xeon L5420s which are common with “low end” providers to Intel Xeon E3s which are extremely common in 2015. Higher end hardware may come at a higher price such as Intel E5-26xx series CPUs.
I have no issues or preference with hardware as long as I feel I am receiving value for what I pay for.
What is OpenVZ?
OpenVZ is one of the most common and most affordable VPS platforms. It allows upgrades “on-the-fly” without reboot and the downside is overselling (running more services than the resources, causing performance delays) is common on OpenVZ however overselling can occur on all virtualization platforms.
What is Xen?
Xen is like OpenVZ however has more flexibility such as eth0 support for VoIP applications where some providers do not enable such support on OpenVZ, more VPN (virtual private network) support and the ability to load additional kernel modules.
What is KVM?
KVM is similar to Xen but is open source. I have no personal preference with Xen and KVM, as I use them equally and feel they’re equally reliable.