Virtual infrastructures are a collection of software-defined components that make up an enterprise IT environment, and allow for the allocation of resources quickly as one can do with digital, versus physical objects. 

This also allows for allocating computing power across multiple systems based on the varying needs you may have as an enterprise, say if you have many different businesses using your single infrastructure in order to power their own operations.
By decoupling physical hardware from an operating system, a virtual infrastructure can help teams achieve greater resource utilization and cost savings. A virtual infrastructure helps small businesses - who can’t afford expensive hardware - acquire reliable cloud-based server space.