To make searching easier, every patent is classified. A classification scheme is a system of codes that groups inventions according to technical area.
Patent offices worldwide use the International Patent Classification (IPC). There are approximately 70 000 different IPC codes for different technical areas.
The European Classification System (ECLA) is an extension of the IPC and is used by the EPO.
Both the IPC and ECLA are divided into eight sections, A-H, which in turn are sub-divided into classes, sub-classes, groups and sub-groups. There are approximately 135 000 classification entries in ECLA.