How to Create Custom Texonomies in Wordpress ?

For Creating Custom Texonomies in Wordpress Have Function
register_taxonomy () Function

Example Code : Below PHP Code Will Create genre texonomy in Wordpress

<?php
add_action( 'init', 'create_book_tax' );

function create_book_tax() {
 register_taxonomy(
  'genre',
  'book',
  array(
   'label' => __( 'Genre' ),
   'rewrite' => array( 'slug' => 'genre' ),
   'hierarchical' => true,
  )
 );
}