VMware essentially allows a single computer to run multiple “virtual machines” (the VM in VMware) simultaneously. Each virtual machine could then run its own operating system with its own applications and software – all from that one single computer. VMware’s software can thus run on a server and essentially share all the hardware resources of the server across multiple OSes and “virtual servers” – which from a user’s perspective looks complete independant.
What is virtualization?
Virtualization is what allows a server to run multiple operating systems and applications on the same time.
Why is this important?
Imagine spending a lot of money on a server – building something so powerful and capable that it has much greater hardware resources than a single operating system requires. This is actually a fairly common occurrence as multi-core / multi-threaded processors have become so powerful. VMware let’s you virtually turn that server into several separate virtual server instances and gives you the ability to run different operating systems should you wish to do so.