From Wikipedia:

> Infrastructure as code (IaC) is the process of managing and
> provisioning computer [data centers][1] through machine-readable
> definition files, rather than physical hardware configuration or
> interactive configuration tools. The [IT infrastructure][2] managed by
> this comprises both physical equipment such as [bare-metal servers][3]
> as well as [virtual machines][4] and associated configuration
> resources. The definitions may be in a [version control system][5]. It
> can use either scripts or declarative definitions, rather than manual
> processes, but the term is more often used to promote [declarative][6]
> approaches.
> 
> IaC approaches are promoted for [cloud computing][7], which is
> sometimes marketed as [infrastructure as a service][8] (IaaS). IaC
> supports IaaS, but should not be confused with it.


  [1]: https://en.wikipedia.org/wiki/Data_center
  [2]: https://en.wikipedia.org/wiki/IT_infrastructure
  [3]: https://en.wikipedia.org/wiki/Bare-metal_server
  [4]: https://en.wikipedia.org/wiki/Virtual_machine
  [5]: https://en.wikipedia.org/wiki/Version_control_system
  [6]: https://en.wikipedia.org/wiki/Declarative_programming
  [7]: https://en.wikipedia.org/wiki/Cloud_computing
  [8]: https://en.wikipedia.org/wiki/Infrastructure_as_a_service