DBus is all about communication. The DBus daemon allows numerous processes to communicate with each other, at the same time, on the same machine. The TOP command will show numerous processes running at the same time. Without DBus, only process at a time would be able to be running.
One of the following commands can be used to view the status of the Dbus daemon.
[root@server1 ~]# service dbus status [root@server1 ~]# systemctl status dbus
DBus lets parts of the system communicate with each other. When you connect a USB device (hardware) to the computer, DBus let's GNOME (software) know about the USB device. DBus let's hardware and software communicate with each other.