Code Adding Widget Ready Areas or Sidebar in WordPress Themes

This is one of the most used ones and many developers already know about this. But it deserves to be in this list for those who don’t know. Paste the following code in your functions.php file: 

// Register Sidebars
function custom_sidebars_widget() {
 
    $args = array(
        'id'            => 'custom_sidebar',
        'name'          => __( 'Custom Widget Area', 'text_domain' ),
        'description'   => __( 'A custom widget area', 'text_domain' ),
        'before_title'  => '<h3 class="widget-title">',
        'after_title'   => '</h3>',
        'before_widget' => '<aside id="%1$s" class="widget %2$s">',
        'after_widget'  => '</aside>',
    );
    register_sidebar( $args );
 
}
add_action( 'widgets_init', 'custom_sidebars_widget' );

You can now visit Appearance » Widgets page and you will see your new custom widget area.

Newly registered widget area in WordPress

To display this sidebar or widget ready area in your theme add this code: 

<?php if ( !function_exists('dynamic_sidebar') || !dynamic_sidebar('custom_sidebar') ) : ?>
<!–Default sidebar info goes here–>
<?php endif; ?>