D-Bus is a service for exchanging messages between applications. In terms of complexity, it can be placed between low-level sockets and CORBA.

D-Bus supports broadcast messages, asynchronous messaging (to reduce latency), authentication, and more. They tried to reduce the overhead: messages are sent over a binary protocol, without using XML. D-Bus also supports associating messages with method calls, but it is not mandatory; this makes using the system quite simple.

There are interfaces for various languages and infrastructures, including GLib, Python, Qt and Java.