A lot of people don't understand electricity. This isn't a criticism, just a short attempt to explain it.

Current is the flow of electricity through a conductor (a wire). Imagine you're floating on a inner tube on a river. A lot of current means you're zipping along with some speed.

Each conductor (wire) has resistance to the current of electricty. That opposes the current. Imagine that same inner tube with you on it, but now flowing fast over rocks. Each bump generates friction and heat but you don't notice it...much unless the current is high...then the ride is very uncomfortable from each bump.

The longer a conductor is, the more resistance it has. This resistance cause voltage to drop in a conductor.

Voltage is the potential to do work. Imagine a huge lake, it's flowing down a waterfall and then feeding the river that's flowing your inner tube along. The huge lake is a potential of water. That's an analogy of voltage.

In a home, if you were to connect a hair dryer to a wall by itself, the cord will get hot. Why? A hair dryer is a heater, and it pulls a lot of current (flow of electricity).

If you were to connect a hair dryer to an extension cord, then the cord would get very hot. The voltage would drop, and in order to continue to feed the same current flow will have to increase more and more. It will kick out the circuit breaker eventually, because a circuit breaker measures current and keeps operations safe.

A fire could happen when too many devices are used on the same plug or if a long extension cord is used on a circuit that need a lot of current, often a heater.

I hope that helps some to clear it up. I made it as simple as possible.