Basically direct current is the operational antonym for Alternating Current (AC). The main distinction being that DC flow does not change directions, and in the case of “pure” DC does not vary at all. Direct current is almost always what is used inside of electronic devices to power the various chips and components, but is considered “bad” or harmful in audio signals, especially those going to speakers. This is because DC produces no sound yet uses a lot of power to be reproduced (remember current flow is constant in DC).
