ISO 11620:2008 specifies the requirements of a performance indicator for libraries and establishes a set of performance indicators to be used by libraries of all types. It also provides guidance on how to implement performance indicators in libraries where such performance indicators are not already in use. The list and descriptions of the performance indicators are also summarized.ISO 11620:2008 provides a standardized terminology and concise definitions of the performance indicators. Furthermore, ISO 11620:2008 contains concise descriptions of the performance indicators and of the collection and the analysis of data needed. ISO 11620:2008 is applicable to all types of libraries in all countries. However, not all performance indicators are applicable to all libraries. Limitations on the applicability of individual performance indicators are also listed for each performance indicator.ISO 11620:2008 does not specify performance indicators for all services, activities, and uses of the resources of the library, either because such performance indicators had not been proposed and tested at the time of formulation of ISO 11620:2008, or because they did not fulfil the criteria specified.