CORBA is a standard defined by OMG that enables systems on different operating systems, languages, and hardware to communicate. It uses IDL to specify interfaces and maps them to implementation languages like Java and C++. CORBA allows programs running on different machines written in different languages to work together over a network like a flight booking system. It uses stubs and skeletons as proxies for remote objects. RMI also enables remote communication between Java applications using stubs on the client side and skeletons on the server side to call methods on remote objects.