do_action( 'wp_footer' )

More Information

The wp_footer action is triggered near the tag of the user’s template by the wp_footer() function. Although this is theme-dependent, it is one of the most essential theme hooks, so it is fairly widely supported.

This hook provides no parameters. You use this hook by having your function echo output to the browser, or by having it perform background tasks. Your functions shouldn’t return, and shouldn’t take any parameters.

This hook is theme-dependent which means that it is up to the author of each WordPress theme to include it. It may not be available on all themes, so you should take this into account when using it.

When included, the default output for this function is the admin panel which will be shown in the top of the theme. It should be kept in the footer for every theme because most of the plugin bind their script files or functions to this hook.

This hook is an action which means that it primarily acts as an event trigger, instead of a content filter. This is a semantic difference, but it will help you to remember what this hook does