VMWare is like having a brand new computer running whatever operating system you require. Only, it is running virtually on your own computer. So I can launch my Windows 8.1 PC and do what I need to do. Then when I need to work with say Rockwell equipment, I boot up a virtual machine running Windows 7 where I have all the relevant software installed. I might have a separate virtual machine for Siemens, and maybe another virtual machine running Win XP for another vendor. This cuts down on the possibility of the Siemens software "breaking" anything on my Rockwell or other systems.
In this example, The Windows 8.1 would be referred to as the "host" operating system. The Windows 7 and Win XP would then be referred to as the "Guest" operating systems. Once you power up that guest, you can do with it whatever you would do with a real computer. Connect USB devices, connect to an Ethernet network. Treat it like a real machine.
OG