Even though this chapter often had a mostly "referential" character, we hope that it gave you insight on how to start writing your own extensions.
You've learned a lot about PHP. You now know how to create dynamic loadable modules and statically linked extensions. You've learned how PHP and Zend deal with internal storage of variables and how you can create and access these variables. You know quite a set of tool functions that do a lot of routine tasks such as printing informational texts, automatically introducing variables to the symbol table, and so on.