You've probably been around electricity your whole life. You know that you plug something in and it turns on, but do you understand how electricity actually works?
Electrical energy is the movement of electrons along a path. Path is called is called a circuit and that movement creates a current. When a current flows through a device, resistance is created. This resistance results in the device doing the work you expect it to do.
Let's look at how resistance creates work in two different electrical devices: a lightbulb and a water heater
Powering a lightbulb
When you flip a light switch on, the light goes on. When you flip the switch off, the light goes off. The switch is what connects the power to the circuit for the current to flow.
The resistance happens in the light itself. The filament in the bulb is made of a material that resists the flow of current. This resistance creates heat, which causes the filament to glow, but not burn up. This is because it's surrounded by a non-flammable gas. That resistance produces light to make the room brighter.
In the case of an incandescent bulb, only 10% of the electricity used creates light — the other 90% is wasted as heat. It's not a very efficient system.
Heating water
In an electric water heater, the heating element resists the flow of current, which creates heat to warm the water in the tank. This is a much more efficient use of electrical energy, with little wasted by-product.
These are two simple examples of how electrical resistance creates work. The same principle applies to any technology, no matter how simple or complex, that uses electricity to operate.