If a theme uses only function calls in it’s template files, it is impossible to make customizations without directly editing the source where the function was defined – most likely in functions.php.

If, however, the theme defines custom actions and filters and uses these in the template files, it is easy to overwrite the core functions of the theme without directly editing the function definitions.

You can define a new function and apply it to the custom action or filter thus adding your customizations without touching the source of the theme.

In the event that the theme becomes outdated and you need to upgrade, your functions will not be overwritten.

Hope this helps to explain.

Just insert into your theme.

The main benefit of this, is that as fellow coders, we can see theres a hook RIGHT THERE, no mysterious functions to follow.

The other benefit is that plugin authors who will eventually follow your example, do the same.. Well.. Then when someone uses a theme that doesnt have the plugin enabled, all hell breaks loose. However, Had you have used do_action(‘custom_action’) instead of custom_action_wrapper(), everything would’ve been fine…….

Yes, Using a custom “Tag” (Its a function, -ok-?) does make things look more inline with the rest of the theme, but it has its downsides.

(Also, Note, Theme authors, please make sure your functions are UNIQUE, say, name them _custom_function(), not my_action_hook(), Another bad plugin developer will come along and use it too, believe me).

Sorry for the rantish comment..