In WordPress, we have inbuilt post types like post, pages, attachments, revisions and changesets.

To create a new custom post type we use register_post_type() function

function mlb_custom_post_type() {
	register_post_type('Movie',
	  array(
		'labels' => array(
			'name'=> __('Movies','textdomain'),
	'singular_name' => __('Movie','textdomain'),
			),
	);
}
add_action('init', 'mlb_custom_post_type');

This will register a new post type Movie which will be created at init hook.

Taxonomies

What are taxonomies in WordPress, it is just a way for classification of things like we use tags and categories.

We can aslo create our own custom taxonomies like for our movies we can categorize them in different genres

function mlb_register_taxonomy_genre()
{
    $labels = array(
        'name'=> _x( 'Genres', 'taxonomy general name' ),
		 'singular_name'=> _x( 'Genre', 'taxonomy singular name' ));

$args = array(
		 'hierarchical'   => false
		 'labels'         => $labels,
		 'show_ui'        => true,
		 'rewrite'        => [ 'slug' => 'genre' ],
	 );

Creating custom post types and taxonomies is the WordPress way of extending its functionality however we want without ever having to touch its core files.