What is the difference between a DC power supply and an AC power supply?

Alternating current is suitable for transmission and distribution of electricity over long distances through the grid system.

Direct current is a one-way flow of charge and is more reliable than alternating current, but is not suitable for long-distance power transmission. Most electronic devices use DC because their voltage is constant, such as devices powered by batteries. Some devices also use rectifiers to convert AC to DC. Power supplies usually have built-in rectifiers and transformers that can raise or lower the voltage to a suitable level.