This is the reference for Hooks explaining all the available hooks of the Contao core and their parameters. The examples in this reference implement Hooks using Service Annotation and Invokable Services. These examples will work out of the box within a Contao 4.9 and 5.x installation as well as in PHP 7 and PHP 8. If your application or extension has a minimum requirement of Contao 4.13 and PHP 8 then you can exchange the annotations with PHP attributes. However, if you need to implement a Hook for Contao 4.4, you still need to use the PHP array configuration. See here for more information on the topic of registering Hooks.