system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The difference between AC and DC current and why there was a whole big debate between what was better. What role did Edison and Tesla play in it all?
gpt
Just one thing, most people have something wrong. 

The ability of electricity to travel efficiently has to do with its voltage. It's more efficient to transmit high voltage than low voltage. In fact, high voltage DC is much more efficient than high voltage AC over long distances. 

The issue is that we don't use high voltage power for most applications because it's dangerous, so we need to step it down. AC power can be stepped down really simply with a device called a transformer, which converts the high voltage into current, and (in theory) is perfectly efficient. 

Stepping down DC is easy too. You use a bigass pair of resistors. The issue is that the excess voltage is lost as heat. It's not efficient at all. 

There are efficient DC to DC converters but they are much more complex to design and the technology didn't really exist during the debate. AC was chosen because of ease of use over long distances, where they could use a few large power plants outside the cities whereas Edison wanted many small power plants in the cities.

Today, really long distance power lines are used with DC transmission because the efficiency on the line outweighs the inefficiency at the neighborhood where an inverter converts the DC into AC. These lines are used in really remote areas and undersea cables.