/wp-content/themes/twentyten/loop.php

<?php
/**
 * The loop that displays posts
 *
 * The loop displays the posts and the post content. See
 * https://developer.wordpress.org/themes/basics/the-loop/ to understand it and
 * https://developer.wordpress.org/themes/basics/template-tags/ to understand
 * the tags used in it.
 *
 * This can be overridden in child themes with loop.php or
 * loop-template.php, where 'template' is the loop context
 * requested by a template. For example, loop-index.php would
 * be used if it exists and we ask for the loop with:
 * <code>get_template_part( 'loop', 'index' );</code>
 *
 * @package WordPress
 * @subpackage Twenty_Ten
 * @since Twenty Ten 1.0
 */
?>

<?php // Display navigation to next/previous pages when applicable. ?>
<?php if ( $wp_query->max_num_pages > 1 ) : ?>
	<div id="nav-above" class="navigation">
		<div class="nav-previous"><?php next_posts_link( __( '<span class="meta-nav">&larr;</span> Older posts', 'twentyten' ) ); ?></div>
		<div class="nav-next"><?php previous_posts_link( __( 'Newer posts <span class="meta-nav">&rarr;</span>', 'twentyten' ) ); ?></div>
	</div><!-- #nav-above -->
<?php endif; ?>

<?php /* If there are no posts to display, such as an empty archive page */ ?>
<?php if ( ! have_posts() ) : ?>
	<div id="post-0" class="post error404 not-found">
		<h1 class="entry-title"><?php _e( 'Not Found', 'twentyten' ); ?></h1>
		<div class="entry-content">
			<p><?php _e( 'Apologies, but no results were found for the requested archive. Perhaps searching will help find a related post.', 'twentyten' ); ?></p>
			<?php get_search_form(); ?>
		</div><!-- .entry-content -->
	</div><!-- #post-0 -->
<?php endif; ?>

<?php
	/*
	 * Start the Loop.
	 *
	 * In Twenty Ten we use the same loop in multiple contexts.
	 * It is broken into three main parts: when we're displaying
	 * posts that are in the gallery category, when we're displaying
	 * posts in the asides category, and finally all other posts.
	 *
	 * Additionally, we sometimes check for whether we are on an
	 * archive page, a search page, etc., allowing for small differences
	 * in the loop on each template without actually duplicating
	 * the rest of the loop that is shared.
	 *
	 * Without further ado, the loop:
	 */
?>
<?php
while ( have_posts() ) :
	the_post();
	?>

	<?php /* How to display posts of the Gallery format. The gallery category is the old way. */ ?>

	<?php if ( ( function_exists( 'get_post_format' ) && 'gallery' == get_post_format( $post->ID ) ) || in_category( _x( 'gallery', 'gallery category slug', 'twentyten' ) ) ) : ?>
		<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
			<h2 class="entry-title"><a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a></h2>

			<div class="entry-meta">
				<?php twentyten_posted_on(); ?>
			</div><!-- .entry-meta -->

			<div class="entry-content">
		<?php if ( post_password_required() ) : ?>
				<?php the_content(); ?>
<?php else : ?>
				<?php
					$images = twentyten_get_gallery_images();
				if ( $images ) :
					$total_images = count( $images );
					$image        = reset( $images );
					?>
					<div class="gallery-thumb">
						<a class="size-thumbnail" href="<?php the_permalink(); ?>"><?php echo wp_get_attachment_image( $image, 'thumbnail' ); ?></a>
					</div><!-- .gallery-thumb -->
					<p><em>
					<?php
						printf(
							/* translators: 1: HTML tag attributes, 2: Image count. */
							_n( 'This gallery contains <a %1$s>%2$s photo</a>.', 'This gallery contains <a %1$s>%2$s photos</a>.', $total_images, 'twentyten' ),
							/* translators: %s: Post title. */
							'href="' . esc_url( get_permalink() ) . '" title="' . esc_attr( sprintf( __( 'Permalink to %s', 'twentyten' ), the_title_attribute( 'echo=0' ) ) ) . '" rel="bookmark"',
							number_format_i18n( $total_images )
						);
					?>
							</em></p>
				<?php endif; // End twentyten_get_gallery_images() check. ?>
						<?php the_excerpt(); ?>
<?php endif; ?>
			</div><!-- .entry-content -->

			<div class="entry-utility">
			<?php
			$gallery = get_term_by( 'slug', _x( 'gallery', 'gallery category slug', 'twentyten' ), 'category' );
			if ( function_exists( 'get_post_format' ) && 'gallery' == get_post_format( $post->ID ) ) :
				?>
				<a href="<?php echo esc_url( get_post_format_link( 'gallery' ) ); ?>" title="<?php esc_attr_e( 'View Galleries', 'twentyten' ); ?>"><?php _e( 'More Galleries', 'twentyten' ); ?></a>
				<span class="meta-sep">|</span>
			<?php elseif ( $gallery && in_category( $gallery->term_id ) ) : ?>
				<a href="<?php echo esc_url( get_category_link( $gallery ) ); ?>" title="<?php esc_attr_e( 'View posts in the Gallery category', 'twentyten' ); ?>"><?php _e( 'More Galleries', 'twentyten' ); ?></a>
				<span class="meta-sep">|</span>
			<?php endif; ?>
				<span class="comments-link"><?php comments_popup_link( __( 'Leave a comment', 'twentyten' ), __( '1 Comment', 'twentyten' ), __( '% Comments', 'twentyten' ) ); ?></span>
				<?php edit_post_link( __( 'Edit', 'twentyten' ), '<span class="meta-sep">|</span> <span class="edit-link">', '</span>' ); ?>
			</div><!-- .entry-utility -->
		</div><!-- #post-<?php the_ID(); ?> -->

		<?php /* How to display posts of the Aside format. The asides category is the old way. */ ?>

	<?php elseif ( ( function_exists( 'get_post_format' ) && 'aside' == get_post_format( $post->ID ) ) || in_category( _x( 'asides', 'asides category slug', 'twentyten' ) ) ) : ?>
		<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

		<?php if ( is_archive() || is_search() ) : // Display excerpts for archives and search. ?>
			<div class="entry-summary">
				<?php the_excerpt(); ?>
			</div><!-- .entry-summary -->
		<?php else : ?>
			<div class="entry-content">
				<?php the_content( __( 'Continue reading <span class="meta-nav">&rarr;</span>', 'twentyten' ) ); ?>
			</div><!-- .entry-content -->
		<?php endif; ?>

			<div class="entry-utility">
				<?php twentyten_posted_on(); ?>
				<span class="meta-sep">|</span>
				<span class="comments-link"><?php comments_popup_link( __( 'Leave a comment', 'twentyten' ), __( '1 Comment', 'twentyten' ), __( '% Comments', 'twentyten' ) ); ?></span>
				<?php edit_post_link( __( 'Edit', 'twentyten' ), '<span class="meta-sep">|</span> <span class="edit-link">', '</span>' ); ?>
			</div><!-- .entry-utility -->
		</div><!-- #post-<?php the_ID(); ?> -->

		<?php /* How to display all other posts. */ ?>

	<?php else : ?>
		<div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
			<h2 class="entry-title"><a href="<?php the_permalink(); ?>" rel="bookmark"><?php the_title(); ?></a></h2>

			<div class="entry-meta">
				<?php twentyten_posted_on(); ?>
			</div><!-- .entry-meta -->

		<?php if ( is_archive() || is_search() ) : // Only display excerpts for archives and search. ?>
			<div class="entry-summary">
				<?php the_excerpt(); ?>
			</div><!-- .entry-summary -->
	<?php else : ?>
			<div class="entry-content">
				<?php the_content( __( 'Continue reading <span class="meta-nav">&rarr;</span>', 'twentyten' ) ); ?>
				<?php
				wp_link_pages(
					array(
						'before' => '<div class="page-link">' . __( 'Pages:', 'twentyten' ),
						'after'  => '</div>',
					)
				);
				?>
			</div><!-- .entry-content -->
	<?php endif; ?>

			<div class="entry-utility">
				<?php if ( count( get_the_category() ) ) : ?>
					<span class="cat-links">
						<?php
						/* translators: 1: CSS classes, 2: Category list. */
						printf( __( '<span class="%1$s">Posted in</span> %2$s', 'twentyten' ), 'entry-utility-prep entry-utility-prep-cat-links', get_the_category_list( ', ' ) );
						?>
					</span>
					<span class="meta-sep">|</span>
				<?php endif; ?>
				<?php
					$tags_list = get_the_tag_list( '', ', ' );
				if ( $tags_list ) :
					?>
				<span class="tag-links">
					<?php
					/* translators: 1: CSS classes, 2: Category list. */
					printf( __( '<span class="%1$s">Tagged</span> %2$s', 'twentyten' ), 'entry-utility-prep entry-utility-prep-tag-links', $tags_list );
					?>
				</span>
				<span class="meta-sep">|</span>
				<?php endif; ?>
				<span class="comments-link"><?php comments_popup_link( __( 'Leave a comment', 'twentyten' ), __( '1 Comment', 'twentyten' ), __( '% Comments', 'twentyten' ) ); ?></span>
				<?php edit_post_link( __( 'Edit', 'twentyten' ), '<span class="meta-sep">|</span> <span class="edit-link">', '</span>' ); ?>
			</div><!-- .entry-utility -->
		</div><!-- #post-<?php the_ID(); ?> -->

		<?php comments_template( '', true ); ?>

	<?php endif; // This was the if statement that broke the loop into three parts based on categories. ?>

<?php endwhile; // End of the loop. Whew. ?>

<?php // Display navigation to next/previous pages when applicable. ?>
<?php if ( $wp_query->max_num_pages > 1 ) : ?>
				<div id="nav-below" class="navigation">
					<div class="nav-previous"><?php next_posts_link( __( '<span class="meta-nav">&larr;</span> Older posts', 'twentyten' ) ); ?></div>
					<div class="nav-next"><?php previous_posts_link( __( 'Newer posts <span class="meta-nav">&rarr;</span>', 'twentyten' ) ); ?></div>
				</div><!-- #nav-below -->
<?php endif; ?>