Virtualization, in one form or another, has been around almost as long as computers. When the term arose in the 1960s, it referred to the partitioning of mainframe computers. But virtualization soon became a way to let people stop worrying about the inner workings of their hardware.
In the earliest days, to put something in a computer’s memory you needed to know the physical location of every byte of storage. Then virtualization tools came along. Instead of deciding to store data in location #84AF, a user could enter a command–LET NAME$= "John Smith"–and allow the compiler to decide where NAME$ would be stored. Shortly after, disk operating systems were invented: Users could assign file names to programs and data; the operating system figured out where to put them.