This chapter is about updating Drupal 7 core— note that means staying within Drupal 7. Appendix A covers upgrading a Drupal 6 site to Drupal 7 if that’s what you need to do. There is a very large difference. A major version upgrade such as Drupal 6 to Drupal 7 will require updating all your modules to be compatible with the version you are upgrading to, your custom theme will need changes, and it will in general take a lot of work to get a complex site working well again. You don't have to worry about any of that here. When updating from 7 point something to 7 point something higher, nothing is supposed to break in the API: all the modules and the theme you are using on the site should continue to work, and as a rule nothing will need to be reconfigured.