[Dr. Scott W. Tinker] So how does electricity get from where it's made to where we use it? Ninety-nine percent of the electricity for homes, schools, buildings, and factories is made in power plants by generators. Then it's transmitted across a massive network we call the electric grid. In fact, in the U.S., there are three grids—one in the East, one in the West, and, of course, one in Texas. But, they all behave pretty much the same. The generator makes electricity, which gets stepped up into extremely high-voltage, and then moved across long distances by large power lines. These go to a distribution center, which steps the voltage down and sends it out to many smaller substations. Substations step it down again and put it on power lines that go through neighborhoods and rural areas. Transformers step it down yet again to a household voltage, where it finally goes in your home for use. This long journey is controlled by utility operators, which are overseen by a regulator. Remember that electricity can't be stored in huge quantities, so we have to generate it right when we need it. That means there are departments of people working around the clock trying to predict the electric load for the day, based on the work people are doing and the amount of air conditioning or heating needed, telling power plants to turn on or shut down to supply more or less power. Working to manage the grid by the second. It's a complicated and incredible system, but that's what it takes to turn on the lights.