I want to add my own <meta /> tag inside the <head></head> container on every page or post within the loop().
Is that possible?
What hook(s) should I use for that?
to hook in the <head> you would use wp_head. You can read the documentation here.
add_action( 'wp_head', 'meta_example' );
function meta_example() {
echo '<meta name="description" content="Meta Description for this Page." />';
} // End meta_example()
This assumes that your theme has <?php wp_head(); ?> in the <head>.
wp_head– Samuel Elh May 24 '16 at 19:01