PHP: WordPress Shortcode

shortcode.php

<?php
add_shortcode( 'basic_shortcode', 'basic_shortcode' );

function basic_shortcode($atts) {
	$atts = shortcode_atts(
		array(
			'title' => 'My Shortcode'
		), $atts);

	ob_start();
	?>
	
	<h3><?php echo $atts['title']; ?></h3>
	
	<?php
	$content = ob_get_clean();

	return $content;
}

// [basic_shortcode title="New Title"]