APPC

The term APPC is an acronym for Advanced Program to Program Communication. It is basically a protocol present in the networking world. This protocol is also known as LU 6.2 in the market, and it was developed as a small but important component of the IBM’s SNA or System Network Architecture. The main role of the APPC or LU 6.2 in the networking and the computing world is that, this protocol gives the ability to the host computer to communicate over a network, which otherwise wouldn’t be possible. The OSI model consists of 7 different layers, however, this APPC protocol is found specifically at the application layer only.

The APPC was designed and developed in such a way that it enables the communications between programs and other applications installed on different computers from portables and workstations to midrange and host computers.
The concept on which the APPC or LU 6.2 protocol works is that the computer in which the protocol is present, in those computers when an application passes the information to the APPC software, the software acts as a translator and translate the request of the application and then pass it to the network interface, for example the LAN adapter.

Once the information has traveled over or through the network and reached its destination, then at that point the information again passes through the APPC software where the information is translated back and after reading that instructions the destined computer would act according with an appropriate reply, set of instructions or bring about the desired result.
Today this protocol is available in IBM and non-IBM operating system, as a part of a separate software, or as a part of the operating system. Still this protocol is mostly present in the IBM operating system as compared to the others.