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

<?php
/**
 * The template used to display Category Archive pages
 *
 * @package WordPress
 * @subpackage Twenty Ten
 * @since 3.0.0
 */
?>

<?php get_header(); ?>

		<div id="container">
			<div id="content" role="main">

				<h1 class="page-title"><?php
					printf( __( 'Category Archives: %s', 'twentyten' ), '<span>' . single_cat_title( '', false ) . '</span>' );
				?></h1>
				<?php
					$categorydesc = category_description();
					if ( ! empty( $categorydesc ) ) {
						echo apply_filters( 'archive_meta', '<div class="archive-meta">' . $categorydesc . '</div>' );
					}
				?>

				<?php
				/* Run the loop for the category page to output the posts.
				 * If you want to overload this in a child theme then include a file
				 * called loop-category.php and that will be used instead.
				 */
				get_template_part( 'loop', 'category' );
				?>

			</div><!-- #content -->
		</div><!-- #container -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>