An IT Service Management System (ITSMS) is a systematic approach to managing the IT services delivered to customers (internal or external). It encompasses people, processes and IT systems.

BSI has published both a code of practice and an auditable specification which represents an industry wide accepted standard based upon the solid foundation of the IT Infrastructure Library (from the Office of Goverment Commerce). This standard, ISO/IEC 20000 (formerly BS 15000) provides an assessment framework and specification for the adoption of an integrated approach to effectively deliver managed IT services to meet the business and customer requirements.