At the very start of the IT revolution, most applications were deployed directly on physical hardware, over the host OS. Because of that single user space, runtime was shared between applications. The deployment was stable, hardware-centric, and had a long maintenance cycle. It was mostly managed by an IT department, and gave much less flexibility to developers. In such cases, the hardware resources were underutilized most of the time. The following diagram depicts such a setup:
Traditional application deployment
For flexible deployments, and in order to better utilize the resources of the host system, virtualization was invented. ...
