ITIL Dictionary of Terms

A - Z Dictionary of terms for ITIL. This is the official Dictionary of terms for ITIL, which is a set of practices for IT Service Management. ITIL® is a registered trade mark of AXELOS Limited. View the Agile Dictionary. Managing Successful Programmes (MSP) Dictionary. Project Office Dictionary (P30). Full PRINCE2 glossary of terms. See also Risk Management Dictionary and Project Management Dictionary.

A - acceptance to availability plan | B - back-out to business unit | C - call to customer-facing service | D - dashboard to driver | E - early life support (ELS) to external service provider | F - facilites management to functional escalation | G - H - gap analysis to hot standby | I - identity to ITIL | J - K - job description to known error record | L - lifecycle to live environment | M - maintainability to monitoring | N - near-shore to notional charging | O - objective to overhead | P - pain value analysis to PRojects IN Controlled Environments (PRINCE2) | Q - qualification to quick win | R - RACI to running costs | S - Sarbanes-Oxley (SOX) to system management | T - tactical to Type III service provider | U - underpinning contract (UC) to utility | V - validation to vulnerability | W - warm standby to workload

T - tactical to Type III service provider


The middle of three levels of planning and delivery (strategic, tactical, operational). Tactical activities include the medium-term plans required to achieve specific objectives, typically over a period of weeks to months.

technical management

(ITIL Service Operation) The function responsible for providing technical skills in support of IT services and management of the IT infrastructure. Technical management defines the roles of support groups, as well as the tools, processes and procedures required.

technical observation (TO)

(ITIL Continual Service Improvement) (ITIL Service Operation) A technique used in service improvement, problem investigation and availability management. Technical support staff meet to monitor the behaviour and performance of an IT service and make recommendations for improvement.

technical support

tension metrics

(ITIL Continual Service Improvement) A set of related metrics, in which improvements to one metric have a negative effect on another. Tension metrics are designed to ensure that an appropriate balance is achieved.

terms of reference (TOR)

(ITIL Service Design) A document specifying the requirements, scope, deliverables, resources and schedule for a project or activity.


(ITIL Service Transition) An activity that verifies that a configuration item, IT service, process etc. meets its specification or agreed requirements. See also acceptance; service validation and testing.

test environment

(ITIL Service Transition) A controlled environment used to test configuration items, releases, IT services, processes etc.

third party

A person, organization or other entity that is not part of the service provider's own organization and is not a customer – for example, a software supplier or a hardware maintenance company. Requirements for third parties are typically specified in contracts that underpin service level agreements. See also underpinning contract.

third-line support

(ITIL Service Operation) The third level in a hierarchy of support groups involved in the resolution of incidents and investigation of problems. Each level contains more specialist skills, or has more time or other resources.


A threat is anything that might exploit a vulnerability. Any potential cause of an incident can be considered a threat. For example, a fire is a threat that could exploit the vulnerability of flammable floor coverings. This term is commonly used in information security management and IT service continuity management, but also applies to other areas such as problem and availability management.


The value of a metric that should cause an alert to be generated or management action to be taken. For example, 'Priority 1 incident not solved within four hours', 'More than five soft disk errors in an hour', or 'More than 10 failed changes in a month'.


(ITIL Service Design) A measure of the number of transactions or other operations performed in a fixed time – for example, 5,000 e-mails sent per hour, or 200 disk I/Os per second.

total cost of ownership (TCO)

(ITIL Service Strategy) A methodology used to help make investment decisions. It assesses the full lifecycle cost of owning a configuration item, not just the initial cost or purchase price. See also total cost of utilization.

total cost of utilization (TCU)

(ITIL Service Strategy) A methodology used to help make investment and service sourcing decisions. Total cost of utilization assesses the full lifecycle cost to the customer of using an IT service. See also total cost of ownership.

total quality management (TQM)

(ITIL Continual Service Improvement) A methodology for managing continual improvement by using a quality management system. Total quality management establishes a culture involving all people in the organization in a process of continual monitoring and improvement.


A discrete function performed by an IT service – for example, transferring money from one bank account to another. A single transaction may involve numerous additions, deletions and modifications of data. Either all of these are completed successfully or none of them is carried out.

transfer cost

(ITIL Service Strategy) A cost type which records expenditure made on behalf of another part of the organization. For example, the IT service provider may pay for an external consultant to be used by the finance department and transfer the cost to them. The IT service provider would record this as a transfer cost.


(ITIL Service Transition) A change in state, corresponding to a movement of an IT service or other configuration item from one lifecycle status to the next.

transition planning and support

(ITIL Service Transition) The process responsible for planning all service transition processes and coordinating the resources that they require.

trend analysis

(ITIL Continual Service Improvement) Analysis of data to identify time-related patterns. Trend analysis is used in problem management to identify common failures or fragile configuration items, and in capacity management as a modelling tool to predict future behaviour. It is also used as a management tool for identifying deficiencies in IT service management processes.


The activity responsible for planning changes to make the most efficient use of resources. Tuning is most commonly used in the context of IT services and components. Tuning is part of capacity management, which also includes performance monitoring and implementation of the required changes. Tuning is also called optimization, particularly in the context of processes and other non-technical resources.

Type I service provider

(ITIL Service Strategy) An internal service provider that is embedded within a business unit. There may be several Type I service providers within an organization.

Type II service provider

(ITIL Service Strategy) An internal service provider that provides shared IT services to more than one business unit. Type II service providers are also known as shared service units.

Type III service provider

(ITIL Service Strategy) A service provider that provides IT services to external customers.

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