Direct current (DC) is an electric current that flows continuously in one direction with a constant voltage polarity, like the steady flow of a river. In contrast, alternating current (AC) periodically reverses direction, with voltage and current oscillating back and forth at a specific frequency, typically 50 to 60 times per second (50-60 Hz). This reversal gives AC a wave- like pattern, while DC shows as a flat line on a graph. DC is commonly produced by batteries, solar cells, and electronic devices, and is used where a constant voltage is required. AC is primarily used for power distribution in homes and industries because its voltage can be easily transformed to higher or lower levels, making long-distance transmission more efficient. In summary, the main difference is the direction of flow: DC flows in one constant direction, while AC alternates direction periodically. Additional characteristics:

• DC voltage is constant, AC voltage varies periodically.
• AC can be easily stepped up/down with transformers; DC cannot.
• AC is more efficient for transmission over long distances.
• DC is often used in electronics and battery-powered devices.

This difference impacts their applications and how electricity is supplied and used in various systems.