functions.php

<?php

if ( ! function_exists( 'twentyeleven_posted_on' ) ) :
/**
 * Prints HTML with meta information for the current post-date/time and author.
 * Create your own twentyeleven_posted_on to override in a child theme
 *
 * @since Twenty Eleven 1.0
 */
function twentyeleven_posted_on() {
	printf( __( '<span class=sep>Posted on </span><a href=%1$s rel=bookmark><time class=entry-date datetime=%3$s>%4$s at %2$s</time></a><span class=by-author> <span class=sep> by </span> <span class="author vcard"><a class="url fn n" href=%5$s title="%6$s" rel=author>%7$s</a></span></span>', 'twentyeleven' ),
		esc_url( get_permalink() ),
		esc_attr( get_the_time() ),
		esc_attr( get_the_date( 'c' ) ),
		esc_html( get_the_date() ),
		esc_url( get_author_posts_url( get_the_author_meta( 'ID' ) ) ),
		sprintf( esc_attr__( 'View all posts by %s', 'twentyeleven' ), get_the_author() ),
		esc_html( get_the_author() )
	);
}
endif;

// necessary to make HTML5 validate - eliminates unnecessary rel attribute link
// UPDATE: no longer necessary for validation, also probably should be inside a function
// remove_action('wp_head', 'rsd_link');

//Try killing the auto-adding of <p> tags. Edit the post to see the difference.
//remove_filter ('the_content', 'wpautop');

// add theme support for HTML5
function twentyeleven_add_html5_support() {
	add_theme_support(
		'html5',
		array(
			'search-form',
			'comment-form',
			'comment-list',
			'gallery',
			'caption',
			'script',
			'style',
		)
	);
}

add_action( 'after_setup_theme', 'twentyeleven_add_html5_support' );