It makes sense to start our exploration of automotive innovation with what has been the heart of the automobile for more than a century: the internal combustion engine. And it makes sense to start a look at the internal combustion engine with the heart of the process: combustion. The very idea of combustion is usually taken for granted, as a notion that is self-explanatory. We all know what combustion is, it’s when something explodes or burns, right? But, thankfully, that’s not exactly what’s taking place in your engine. We’re going to need a more precise understanding of exactly what and how something is burned in an engine before we can understand the complete workings of internal combustion.