sepoto on "How to find the definition of wp_head"

Inside my themes header.php I have:

<?php wp_head(); ?>

From what I understand the definition of wp_head is inside

wp-includes/general_template.php which includes some text:

do_action( 'wp_head' );

So I am told that wp_head is defined somewhere by add_action howver I have no idea where I should begin to look for the call to add_action. Where is the final definition of wp_head?

Thank you