# A mental model of how Futures and runtimes work The main goal in this part is to build a high level mental model of how the different pieces we read about in the previous chapter works together. I hope this will make it easier to understand the high level concepts before we take a deep dive into topics like trait objects and generators in the next few chapters. This is not the only way to create a model of an async system since we're making assumptions on runtime specifics that can vary a great deal. It's the way I found it easiest to build upon and it's relevant for understanding a lot of real implementations you'll find in the async ecosystem. Finally, please note that the code itself is "pseudo-rust" due to the need for brevity and clarity. >Click on a page to open a larger view in a new tab.