Which is true of direct current (DC)?

The characteristic that defines direct current (DC) is that the current flows in one direction consistently. This unidirectional flow of electric charge is fundamental to the nature of DC and differentiates it from alternating current (AC), where the current periodically reverses direction. DC is commonly used in various applications, such as in batteries, electronic devices, and photovoltaic systems, precisely because it provides a stable and constant voltage or current output.

In contrast, alternating current switches direction, and while some forms of DC may be stored (like in batteries), not all forms of energy are used exclusively in large power stations. This clarity about DC's nature helps one to understand its essential role in electronics and power systems.