WordPress/wp-content/themes/twentyfourteen/tag.php

<?php
/**
 * The template for displaying Tag pages.
 *
 * Used to display archive-type pages for posts in a tag.
 *
 * Learn more: http://codex.wordpress.org/Template_Hierarchy
 *
 * @package WordPress
 * @subpackage Twenty_Fourteen
 */

get_header(); ?>

	<section id="primary" class="content-area">
		<div id="content" class="site-content" role="main">

			<?php if ( have_posts() ) : ?>

			<header class="archive-header">
				<h1 class="archive-title"><?php single_tag_title();; ?></h1>

				<?php
					// Show an optional term description.
					$term_description = term_description();
					if ( ! empty( $term_description ) ) :
						printf( '<div class="taxonomy-description">%s</div>', $term_description );
					endif;
				?>
			</header><!-- .archive-header -->

			<?php
					while ( have_posts() ) :
						the_post();

						get_template_part( 'content', get_post_format() );
					endwhile;
					twentyfourteen_paging_nav();

				else :
					get_template_part( 'content', 'none' );

				endif;
			?>
		</div><!-- #content -->
	</section><!-- #primary -->

<?php
get_sidebar( 'content' );
get_sidebar();
get_footer();