ITIL Functions :
Function is a team or a group of people who perform a set of activities.
ITIL v3 defines four functions as
Service Desk,
Application management,
Technical Management, and
Operations Management.
4 ITIL v3 Functions
Service desk :
This is a function who will be the first point or single point of contact for end user issues.
Application management :
This is a function who will manage the application development and maintenance issues.
Technical management :
This is a function who will manage the technical expertise for the ITSM processes and operations.
Operations management :
This is a function who will manage the day to day operations with respect to IT operations control and IT facilities management.