?Specifically, the electricity we use in our homes?
As usual, to give an answer, we need to explain some basic things first. Electromagnetism is weird. But it is handy. For the moment, all we need to say is that when you move a magnet, the electromagnetic field around that magnet also moves, and any electrons in a nearby wire will also move. It is like the EM field is connecting the magnet to nearby electrons. Similarly, when you have electrons moving in a current through a wire (aka electricity,) the electromagnetic field they are a part of is also moving, which means any magnets in that EM field will also want to move. Neat! This is handy! This means that if I have wires bringing electricity into my house, I can use those wires to move magnets. Moving magnets can cause vibrations in the air from my computer speakers. Moving magnets can turn the blades of the fan in my air conditioner. They can turn the wheels in my electric car. They can do many useful things!
So, where does it all come from? There are three options, two which involve chemistry. The first is a chemical battery. You take two substances, one which has electrons it doesn't need, and one which needs electrons. If you connect those two with a wire, the electrons will move from the one to the other. This line of moving electrons through a wire is electricity. This is not how most household electricity is generated, but it is how most of our batteries work.
The second method uses an exothermic reaction. All this means is that we take something that can burn. In combustion reactions (burning) a fuel is combined with a small amount of heat to start the reaction and some oxygen. The new reaction releases even more heat. This is helpful, because we can use that heat to boil something like water. As the water boils, it produces water vapor that rises and expands. If we put some sort of fan blades above the boiling water, as the steam rises, the molecules of water vapor will hit the fan and turn it...if we attach a magnet to the turning fan blade, then we have a moving magnet. Have some nearby wires, and the moving magnet will cause an electrical current in the wire. Voila! From burning fuel, we get electricity that then can be run all over the place to homes everywhere! This is how many of our power plants work. They burn fossil fuels like coal, or natural gas, or refined petroleum/oil products, use the heat the boil water, use the water to turn fans (aka turbines) that turn magnets that make electricity. The problem, of course, is that those fuels release literally millions of tons of carbon dioxide into the atmosphere, heavily contributing to global warming.
The third option relies not on a chemical reaction, but on nuclear reactions. If we take radioactive materials, as they break apart, they release heat. Just as before, if we use that heat to boil water, we can make electricity. On the up side, this doesn't contribute to greenhouse gases and global warming, because we're not burning anything. On the down side, we end up left with a bunch of materials that aren't radioactive enough to be useful for generating more power, but are radioactive enough to be super dangerous. So far, we have done a really bad job of finding good places to store this waste, because...uh. Well, no one wants it in their backyard. Or state, for that matter. Also, if something goes badly wrong at a Nuclear Power Plant, it can blow up and poison a large area with radioactive materials.
In any case, here in Illinois, about half our power comes from Nuclear plants, and about half from Coal burning plants. So, we're doing a decent job of hurting our environment either way. There are of course other alternatives like solar, but those barely contribute to the power we use.
Smile!