The CI-V protocol is a communication standard developed by Icom, a Japanese company that specializes in amateur radio equipment. CI-V is used to control and communicate with Icom devices, such as transceivers, receivers, and other amateur radio equipment. The protocol uses a master-slave architecture, where the computer acts as the master and the device acts as the slave. The CI-V protocol allows for a range of functions, including setting frequencies, adjusting volume, and retrieving device status.