What type of electrical current did Tesla champion over Edison's direct current?

Tesla championed alternating current over Edison's direct current. Alternating current periodically reverses direction, while direct current flows steadily in one direction.

The key advantage of AC was transmission efficiency. Transformers can raise AC to very high voltages for long-distance transmission and then lower it for homes and businesses. Higher transmission voltages reduce energy lost as heat in wires, making AC practical for large electric grids.

Tesla developed and promoted polyphase AC motors and power systems, while George Westinghouse backed his patents and helped commercialize them. The rivalry became known as the “War of the Currents,” with Edison supporting DC and publicly highlighting safety concerns about high-voltage AC.

The outcome was not that DC disappeared: batteries, electronics, and many modern devices still use it. However, AC became the standard for electricity distribution because it could be transformed efficiently across a large network.