<!-- BEGIN COPY / PASTE -->
    // JavaScript: Register the block
    wp.blocks.registerBlockType('my-plugin/dynamic-block', {
      title: 'Dynamic Block',
      icon: 'smiley',
      category: 'widgets',
      edit: function(props) {
        return wp.element.createElement('p', {}, 'Dynamic content will appear here.');
      },
      save: function() {
        return null; // Server-side rendering
      }
    });

    // PHP: Server-side rendering
    function my_dynamic_block_render_callback($attributes) {
      // Fetch dynamic content
      $dynamic_content = get_some_dynamic_content();
      return '<p>' . esc_html($dynamic_content) . '</p>';
    }
    register_block_type('my-plugin/dynamic-block', array(
      'render_callback' => 'my_dynamic_block_render_callback',
    ));
    <!-- END COPY / PASTE -->