You didn't think you were ever going to see this heading did you? This chapter has been very long but highly theoretical. We haven't built anything fun and the only code we saw was to exemplify most of the things we talked about. It was a difficult chapter as it covered many complex aspects of data storage and handling. But trust me, these things are important to know and this chapter can serve both as a starting point to dig deeper into the code and a reference to get back to when unsure of certain aspects.
We saw what the main options for storing data in Drupal 8 are. Ranging from the State API all the way to entities, you have a host of alternatives. After covering the more simple ways, such as the State API, the private and shared tempstores and the UserData API, we dove a bit more into the configuration system, which is a very important one to understand...