AC vs DC

There are two fundamental kinds of current. DC (Direct Current) flows steadily in one direction — the kind batteries, USB and solar panels provide, and the kind every chip and LED expects. AC (Alternating Current) reverses direction many times a second — the kind that comes out of a wall socket.

Picture water in a pipe. DC is water flowing one way like a river — steady and predictable. AC is water sloshing back and forth like a tide — energy still gets delivered, but the flow keeps reversing. Both can power things; they just move differently.

AC can be stepped up or down efficiently with transformers. Steady DC does not directly drive an ordinary transformer, but switched converters can change DC voltage, and high-voltage DC is also used for long-distance transmission. Household mains remains hazardous after distribution voltage is stepped down.