DCC is short for DIGITAL COMMAND CONTROL. It is not just another method of control, it is a standard for manufacturers to use to make their products compatible with other products on the market that meet this standard. In this respect, the playing field has been leveled and we can begin to reap the benefits of controlling things that we have never been able to control before.

The DCC signal is an alternating DC waveform, which contains the digital information, This coded signal controls a specific decoder placed in a specific locomotive causing it to use as much of the track voltage as it needs to move forward or backward, turn its headlight on or off or even dim it for meets with other trains on another track. Decoders can be set so that locomotives that could never have run together with a conventional power pack can doublehead or even operate in pusher service without one of the locos working too hard or not hard enough. Many of the newest locomotives have light boards that can be removed, and a decoder added in the same space. (Source: NMRA)