You may know that it comes from the power lines out at front of your house, but you may not know the level of complexity required to get this electricity to your house from such a long distance away.
When power of a relatively low voltage, such as 240 volts, is sent through very long wires, by the time the it gets to the other end, a lot of the energy is lost as it is converted to heat in the wires.
The voltage drop or difference from one end to the other can be very significant at these low voltages. So if your power was generated at the power plant at 240 volts and sent along the power lines, for many kilometres at 240 volts, by the time it arrived at you house the voltage would not be high enough to power your devices that are designed to run on 240 volts.
When power of a relatively high voltage is sent through the same wires, the losses and hence the voltage-drop is a much smaller percentage. This phenomenon is used in order to get the electricity to your house without significant losses.
The power is generated at the power plant at a relatively low voltage. It is then sent into very large transformers and 'stepped up' to a much higher voltage. These transformers are similar to the plug packs or 'wall warts' that we use in the home to power many devices such as laptops or battery chargers but they are much larger.
It is then sent along special, very large, high voltage lines for very long distances, across the state and across the country. These types of lines have huge steel frame towers, with multiple arms and the wires are suspended very high in the air. They can often be seen in less densely populated areas at the edge of towns or suburbs. They also often have linear parks below, following their course through suburban areas to minimize exposure to electromagnetic radiation for nearby residents.
When it reaches a local destination it is then 'stepped down' again also through very large transformers and then distributed locally at 240 volts, over relatively short distances. The sites where these transformers are located are called substations and can be seen dotted around all suburbs. Some industrial factories have their own because they use so much power.
Through this method of power distribution transmission losses are minimised and we are not wasting lots of hard won electrical power just to get it to where it needs to go.