The term Plug & Play (connect and use) is very common in computer science and usually refers to a device (for example with a USB connector) that connects to the PC without having to install additional software.
The term is also spreading in the marine sector to indicate a mode of interface between the various devices of the boat where the connectors are already prepared for a prompt connection and where the main unit is able to automatically recognize the features added to the system.
The NMEA 2000 interface protocol has been designed with plug & play features, in fact the connectors have been standardized, however the recognition of the new connected device depends on the software of the main unit.