The International Patent Classification (IPC) is an internationally recognized classification system, maintained by the World Intellectual Property Organization (WIPO) and assigned to patent documents by the various patent offices around the world. The IPC is widely used throughout the world (although less so in the United States).
There are eight distinct sections of the IPC (lettered A-H) and these sections are further subdivided into classes. Each class consists of the section letter, followed by two digits. For example, section A21 is the class for Baking; Edible Goods, and G02 is the class for Optics.