It was created under the Strasbourg Agreement (1971), one of a number of treaties administered by the World Intellectual Property Organization (WIPO).
The classification is updated on a regular basis by a Committee of Experts, consisting of representatives of the Contracting States of that Agreement with observers from other organisations, such as the European Patent Office.
Patent publications from all of the Contracting States (and also most others) are each assigned at least one classification symbol indicating the subject to which the invention relates and may also be assigned further classification symbols and indexing codes to give further details of the contents.
In 1967, BIRPI, WIPO's predecessor, and the Council of Europe began negotiations aiming to "internationalize" the International Classification.
With the eighth edition, which came into force January 1, 2006, the system was revised and the classification was divided into "core" and "advanced" levels.