An integrated library system (ILS) integrates the major functions of a library including circulation, acquisitions, cataloging, serials control, and providing access to resources through the online public access catalog (OPAC). Key elements of an ILS are the ability to handle standard formats like MARC, maintain authority records, link to bibliographic utilities, and integrate records. The average lifespan of an ILS is 3-5 years and the industry has seen much consolidation in recent years, impacting libraries through changes, training, and budgets.