# Extension guide
Welcome to the extension guide! This page will show you how to create extension modules for Herodot, no matter whether it's a simple extension inside your application, or a fully-fledged, composer-distributed package.
# Why we need PHP 8
With PHP 8, lots of super-cool features have been added to the language. What stands out in regard to documentation, though, are
attributes (opens new window): They allow adding structured metadata to declarations in code, without any runtime
overhead. Finally, this makes it possible to swap out docblock annotations with actual code that can be validated, type-hinted and highlighted by IDEs!
As this is most likely the future of annotating code, we made it a strict requirement.
If you can't migrate to PHP 8 just yet, we recommend one of the alternatives listed at the top of this document.