WordPress get category ID

wordpress-get-category-id-wp-query.php

<?php

// Get the "featured" category object.
$featured_category = get_term_by( 'slug', 'featured', 'category' );

// Set the "featured" category ID.
$featured_category_ID = $featured_category->term_id;

// Get the latest three posts, ignoring the current post
// and any in the "featured" category.
$args = array(
	'post_type'              => 'post',
	'posts_per_page'         => 3,
	'post__not_in'           => array( get_the_ID() ),
	'category__not_in'       => array( absint( $featured_category_ID ) ),
	'no_found_rows'          => true,
	'update_post_meta_cache' => false,
	'update_post_term_cache' => false,
);

// Run query.
$data = new WP_Query( $args );