IT as a service (ITaaS) is an operational model where the information technology (IT) service provider delivers an information technology service to a business.   The IT service provider can be an internal IT organization or an external IT services company. The recipients of ITaaS can be a line of business (LOB) organization within an enterprise or small and medium business (SMB). The information technology is typically delivered to a managed service with a clear IT services catalog and pricing associated with each of the catalog items. At its core, ITaaS is a competitive business model where businesses have many options for IT services and the internal IT organization has to compete with those other external options in order to the selected IT service provider to the business. Options for providers other than the internal IT organization may include IT outsourcingcompanies and public cloud providers.
Under an ITaaS model, the IT service provider will place a great emphasis on the needs and the outcomes required by the business to improve productivity and improving the top line (revenue) and bottom line (profitability). Such services will have a strong industry focus to fully enable industry specific use cases. The benefits of using the ITaaS model include the standardization and simplification of products delivered by IT, improved financial transparency and more direct Products from external providers.
Not a cloud service model
According to the NIST Definition of Cloud Computing ,  there are three service models associated with cloud computing: infrastructure as a service (IaaS), platform as a service (PaaS), and software as a service (SaaS). The concept of ITaaS as an operating model is not limited to or dependent on cloud computing. IaaS, PaaS, and SaaS. IaaS, PaaS, and SaaS. IaaS, PaaS, and SaaS. EMC,  Citrix,  and VMware. 
ITaaS is not a technology shift – such as a move to increase the use of virtualization . Rather, it is an operational and organizational shift to running IT production for business consumption. IT organizations that adopt ITaaS are most likely to use the best practices for IT service management as defined in the Information Technology Infrastructure Library .
Transformation to IT as a service
Several vendors who are proponents of ITaaS describe the transition from an IT organization to the ITaaS model as a journey which includes the adoption of such models as:
- New technology models based on the use of private, public, and hybrid clouds; Employing controls, trust and compliance up and down the stack; Introducing infrastructure standardization and automation wherever possible.
- New consumption models; self-service catalogs; Providing financial transparency for costs and pricing; Offering consumerized IT – how to bring your own device (BYoD) – to meet the needs of users. All of which simplify and encourage consumption of services.
- New business models which imply a revised organization, with new business and technical skills and roles; Creation of more horizontal, service-oriented processes; Explicit IT alignment with lines-of-business.
- Business Driven IT solution is Represented as a repeatable business activity Having a specified outcome, où Service acts as a self-contained logical unit, May be Composed of other services (choreography), is Generally a ” black box ” to typical Consumers while highly transparent To leadership.
- Jump up^ “An IT-as-a-Service Handbook: Ten Key Steps on the Journey to ITaaS” (PDF) . Www.emc.com . June 2012.
- Jump up^ http://www.peterhinssen.com/downloads/printmedia/179/08_it_as_a_service.pdf
- Jump up^ National Institute of Standards and Technology Special Publication 800-145
- Jump up^ ITaaS for the CIO
- Jump up^ Citrix Whitepaper on ITaaS
- Jump up^ VMWare Start your Journey to the Cloud