OPC is the interoperability standard for secure and reliable data exchange in the world of industrial automation. It intends to provide a smooth flow of information, on a platform independent basis, between devices and systems from different vendors.
In other words, OPC is an interpreter standing in between the devices on site and the clients (systems, devices, applications, etc.) trying to communicate these devices. Each device speaking its own language, the clients are supposed to speak its language in order to be able to read data from or to write data to a device. If there are devices from multiple vendors on site, then the clients must be able to speak each language. But if there is OPC, clients will just need to know the OPC language so that they can send their requests to OPC and it will translate and transfer all requests to the target devices.
OPC was first released in 1996. Back then it was restricted to Windows OS only and the abbreviation OPC meant “OLE (Object Linking and Embedding) for Process Control”. Today, these older specifications are known as OPC Classic.
Then in 2008, the OPC UA (Unified Architecture) was released to address the new challenges in the industry. It comes with a platform independent and service-oriented architecture and supports all specifications of OPC Classic. Today the abbreviation OPC stands for “Open Platform Communications”.
The standard is developed and maintained by the OPC foundation. You can check the OPC foundation website for details. You can become a member, follow the news and events, certify for the standards and even contribute to the development.