Welcome to the last of four courses in this session in energy. My name is Martin Cat Stevens, and by now, you've learned quite a few things about electricity, natural gas, safety in the workplace. In this last session, what we're going to try to do is give you some perspective on the energy industry and some of the more interesting topics that I find truly fascinating that I think you will as well. In this particular course, we're going to be touching on a number of interesting topics, and in no particular order, they will include embedded or embodied energy, energy security, hydrofracking, natural gas as a feedstock to the petrochemical industry, stored sunlight, demand response, energy's role in national competitiveness, predictive analytics, and climate change. Now, these topics don't sound like they have a lot to do with each other. But, I think you'll find that we'll present them in a way which is both interesting and relevant to your career. In this course, we also have Mr. Dennis Allison Beck, who is a longtime friend of mine, someone who's been in the energy industry for more than 30 years, works in utilities, and now is a consultant at a law firm, and he brings remarkable information and perspective to this discussion as well. I think you'll enjoy listening from him as well. Energy is one of those topics that everybody feels like they have a pretty good grasp of, and if you take a card look at energy, you'll realize that it's a very complex and abstract idea. Why? Because there is nothing that we call pure energy and nothing that we can put it in a bottle and say, "That's energy, and this is not energy." For instance, if we take a heavy weight and place it up on a shelf, it has the potential to do work, so we say it has potential energy. So, I can sit on that shelf for years, decades, millennia, and at some point though, if it falls down, it will crush an apple or do some other kind of useful work, and so that is called potential energy. You can think of potential energy also wrapped up into a piece of firewood because they can sit around for a long time too. But when you finally eventually get around to burning it, you can produce heat, and heat can produce steam, and steam can turn turbines and the like. So, there's this idea of potential energy and its entrapped in lots of different material objects. Then, there's the motion of energy. So, a heavy ball rolling at a certain velocity, it also has the ability to do work. It's called kinetic energy because it's moving. So, we have water falling off a waterfall or tumbling through a stream, and turning a turbine. So, energy is always associated with the material system and in that way, it broadens the scope of what we call energy. We'll get into more of the different types of energy in a minute and where they come from. But don't be afraid if you think energy is abstract because it is abstract in reality. By the time we're done with this course, you'll see how in many different ways energy can be harnessed, trapped, stored and the like.