OpcEnum (OPC Enumerator) is a software application that provides information about each OPC Server that resides on a PC. OPC Client applications (such as HMIs, Historians, various automation/process control applications, etc) use OpcEnum to browse (discover) the OPC Server applications that are available on the target PC. This enables users to easily connect to various OPC Servers. OpcEnum retrieves its information from the Windows Registry. Consequently, OpcEnum can only reveal information about local OPC Servers (i.e. the OPC Servers and OpcEnum must reside on the same PC). The OpcEnum executable is opcenum.exe. OpcEnum provides the Program Identifier (ProgID) and Globally Unique Identifier (GUID) for each OPC Server on the PC. The OPC Foundation is responsible for the development of OpcEnum, and provides OpcEnum for free.