Display WordPress Posts from Specific Category by Category Id or Slug

Do you want to display WordPress Posts from the Specific Category by Category Id?

    $cat_id = 3; 
    $args = array(
       'post_type' => 'post' ,
       'orderby' => 'date' ,
       'order' => 'DESC' ,
       'posts_per_page' => 6,
       'cat'         => $cat_id,
       'paged' => get_query_var('paged'),
       'post_parent' => $parent
   ); 

   $q = new WP_Query($args);
   if ( $q->have_posts() ) { 
     while ( $q->have_posts() ) {
     $q->the_post();
     ?>
       

          the_post_thumbnail(); ?>
          

          
          
Read more
          

          

       
 
If you want to show posts with category slug instead of category id then
Replace
'cat'         => $cat_id,
with
'category_name' => 'my-category-slug',
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