function portfolio_register() {

    $labels = array(

        'name' => _x('Portfolio', 'post type general name'),

        'singular_name' => _x('Portfolio Item', 'post type singular name'),

        'add_new' => _x('Add New', 'portfolio item'),

        'add_new_item' => __('Add New Portfolio Item'),

        'edit_item' => __('Edit Portfolio Item'),

        'new_item' => __('New Portfolio Item'),

        'view_item' => __('View Portfolio Item'),

        'search_items' => __('Search Portfolio Items'),

        'not_found' =>  __('Nothing found'),

        'not_found_in_trash' => __('Nothing found in Trash'),

        'parent_item_colon' => ''

    );

    $args = array(

        'labels' => $labels,

        'public' => true,

        'publicly_queryable' => true,

        'show_ui' => true,

        'query_var' => true,

        'rewrite' => true,

        'capability_type' => 'post',

        'hierarchical' => false,

        'menu_position' => 8,

        'supports' => array('title','editor','thumbnail')

    ); 

    register_post_type( 'portfolio' , $args );

}

add_action('init', 'portfolio_register');

function create_portfolio_taxonomies() {

    $labels = array(

        'name'              => _x( 'Categories', 'taxonomy general name' ),

        'singular_name'     => _x( 'Category', 'taxonomy singular name' ),

        'search_items'      => __( 'Search Categories' ),

        'all_items'         => __( 'All Categories' ),

        'parent_item'       => __( 'Parent Category' ),

        'parent_item_colon' => __( 'Parent Category:' ),

        'edit_item'         => __( 'Edit Category' ),

        'update_item'       => __( 'Update Category' ),

        'add_new_item'      => __( 'Add New Category' ),

        'new_item_name'     => __( 'New Category Name' ),

        'menu_name'         => __( 'Categories' ),

    );

    $args = array(

        'hierarchical'      => true, // Set this to 'false' for non-hierarchical taxonomy (like tags)

        'labels'            => $labels,

        'show_ui'           => true,

        'show_admin_column' => true,

        'query_var'         => true,

        'rewrite'           => array( 'slug' => 'categories' ),

    );

    register_taxonomy( 'portfolio_categories', array( 'portfolio' ), $args );

}

add_action( 'init', 'create_portfolio_taxonomies', 0 );

/*********** display the page in using template .php in wordpress ********/

<?php

$taxonomy = 'portfolio_categories';
$terms = get_terms($taxonomy); // Get all terms of a taxonomy

if ( $terms && !is_wp_error( $terms ) ) :
?>
    <ul>
        <?php foreach ( $terms as $term ) { ?>
            <li><a href="<?php echo get_term_link($term->slug, $taxonomy); ?>"><?php echo $term->name; ?></a></li>
        <?php } ?>
    </ul>
<?php endif;?>

?>

<?php echo get_the_term_list(get_the_ID(), 'portfolio_category', '', ', ', ''); ?>

/******** or this display in template page **********/

<?php
  $args = array(
  'post_type' => 'project',
   'tax_query' => array(
    array(
    'taxonomy' => 'Initiatieffase',
     'field' => 'slug',
      'terms' => 'bob'
       )
     )
  );
$query = new WP_Query( $args );
$loop = new WP_Query($args);
while ($loop->have_posts()) : $loop->the_post(); ?>
<li>
 <a href="<?php the_permalink(); ?>"><?php the_post_thumbnail(); ?></a></li>
<?php endwhile; ?>
<?php wp_reset_postdata(); ?>

/******** or this display in template page **********/

<?php 

$args = array( 'posts_per_page' => 5,'post_type' => 'work','category' => 15 );

$myposts = get_posts( $args );
foreach ( $myposts as $post ):?>
<li>
    <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
</li>
<?php endforeach; ?>

 // Our custom post type function