A dummy is a dummy or a replica. In the hardware field, a dummy can be, for example, a load resistor at the output of a mobile radio transmitter that simulates the impedance characteristics of an antenna or a transmission line.
An artificial load replica is called a dummy load. It is used, for example, when leveling or repairing a transmitter system, and is used when the transmitter is not supposed to radiate high- frequency signals.
In software and especially in data networks, dummies are usually fill characters of any kind that have to be inserted for logical or formal reasons. For example, in Ethernet the padding of data blocks that are too short( pad) and the insertion ofbits or characters in the form of a bit fill or character fill in other data packet blocks is an example of the use of dummies.