What Is IT Infrastructure: A Definition and a Taxonomy

There are probably as many definitions of IT Infrastructure as there are IT organizations.  I believe the following definitions are representative and appropriate:

IT Infrastructure.. "IT infrastructure consists of the equipment, systems, software, and services used in common across an organization, regardless of mission/program/project.  IT Infrastructure also serves as the foundation upon which mission/program/project-specific systems and capabilities are built." from cio.gov

ITIL defines infrastructure more like:    All of the components (Configuration Items) that are needed to deliver IT Services to customers. The IT Infrastructure consists of more than just hardware and software.

Additionally, for project planning purposes I believe IT Infrastructure should be subdivided into into several components:

  1. Software Development
  2. Software Maintenance (corrective perfective, adaptive, block changes)
  3. Purchased Software (e.g. ERP system)
  4. IT Infrastructure hardware (e.g. servers, switches)
  5. IT Services (e.g software setup, help desk, computer administration)

Further, there are two major divisions of labor: the project and ongoing operations:

  • Project: The project is the portion of the system life cycle where the system is developmental, that is where it is not yet in operation.
  • Ongoing Operations: The ongoing operations is the portion of the system life cycle where the system is deployed to users

Of course these major activities need to be further subdivided for detailed analysis and planning purposes.