Understanding load_template() and get_template_part() in WordPress

WordPress theme development uses several helper functions for template loading, and the two names that come up most often are load_template() and get_template_part(). They are both more powerful than a simple PHP include, and understanding the differences between them helps a lot when organizing templates cleanly.

get_template_part(): a higher-level wrapper around load_template()

get_template_part() is essentially a higher-level wrapper built on top of WordPress’s template-loading system. It allows themes to look for a more specific template first, then fall back to a generic one if the specific file does not exist. That gives themes a useful form of built-in fault tolerance.

At a high level, its source code works like this:

function get_template_part( $slug, $name = null ) {
	do_action( "get_template_part_{$slug}", $slug, $name );

	$templates = array();
	$name = (string) $name;
	if ( '' !== $name )
		$templates[] = "{$slug}-{$name}.php";

	$templates[] = "{$slug}.php";

	locate_template($templates, true, false);
}

get_header(): template loading with hooks and extension support

Many people assume that get_header() is just a more advanced version of get_template_part(), but that is not quite right. Its most important difference is that it fires the get_header hook before loading templates. That hook is important for compatibility with plugins or other theme logic.

The source code looks roughly like this:

function get_header( $name = null ) {
	/**
	 * Fires before the header template file is loaded.
	 */
	do_action( 'get_header', $name );

	$templates = array();
	$name = (string) $name;
	if ( '' !== $name )
		$templates[] = "header-{$name}.php";

	$templates[] = 'header.php';

	if ('' == locate_template($templates, true))
		load_template( ABSPATH . WPINC . '/theme-compat/header.php');
}

By default, this loads header.php, but it also supports a named variation such as get_header('home'), which would load header-home.php if present. The related functions get_footer() and get_sidebar() work in the same general way.

Because of that hook, using get_template_part('header') as a substitute for get_header() is not really correct. It may look similar, but it skips do_action( 'get_header', $name ), which can break compatibility with plugins or theme integrations that rely on that hook.

get_template_part('header')
get_template_part('header')

Template loading priority and how fallback works

The main strength of get_template_part() is that it tries a more specific template file first, then falls back to a generic one. For example:

get_template_part('content', 'product')

That call first looks for content-product.php. If that file does not exist, it falls back to content.php.

Why not just use PHP include() directly?

It is worth flipping the question around: why use plain PHP includes at all when WordPress already provides a safer template-loading system? In fact, I have seen developers build good themes with raw include calls. It works.

But plain includes do not provide the fallback behavior that WordPress template loading supports. They also do not integrate as cleanly with WordPress’s own conventions and hooks. That is why functions such as get_template_part(), get_header(), and load_template() are usually the better choice for theme development.