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

<?php
/**
 * The template for displaying Category pages
 *
 * @link https://developer.wordpress.org/themes/basics/template-hierarchy/
 *
 * @package WordPress
 * @subpackage Twenty_Fourteen
 * @since Twenty Fourteen 1.0
 */

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 printf( __( 'Category Archives: %s', 'twentyfourteen' ), single_cat_title( '', false ) ); ?></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
					// Start the Loop.
				while ( have_posts() ) :
					the_post();

					/*
					* Include the post format-specific template for the content. If you want to
					* use this in a child theme, then include a file called content-___.php
					* (where ___ is the post format) and that will be used instead.
					*/
					get_template_part( 'content', get_post_format() );

					endwhile;
					// Previous/next page navigation.
					twentyfourteen_paging_nav();

				else :
					// If no content, include the "No posts found" template.
					get_template_part( 'content', 'none' );

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

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