diff --git a/wp-admin/includes/update.php b/wp-admin/includes/update.php
index 74899e37cb..306745d864 100644
--- a/wp-admin/includes/update.php
+++ b/wp-admin/includes/update.php
@@ -200,6 +200,7 @@ function core_update_footer( $msg = '' ) {
 
 	switch ( $cur->response ) {
 	case 'development' :
+		/* translators: 1: WordPress version number, 2: WordPress updates admin screen URL */
 		return sprintf( __( 'You are using a development version (%1$s). Cool! Please <a href="%2$s">stay updated</a>.' ), get_bloginfo( 'version', 'display' ), network_admin_url( 'update-core.php' ) );
 
 	case 'upgrade' :
diff --git a/wp-admin/includes/upgrade.php b/wp-admin/includes/upgrade.php
index 63c59a4565..94a122509c 100644
--- a/wp-admin/includes/upgrade.php
+++ b/wp-admin/includes/upgrade.php
@@ -375,6 +375,7 @@ function wp_new_blog_notification($blog_title, $blog_url, $user_id, $password) {
 	$email = $user->user_email;
 	$name = $user->user_login;
 	$login_url = wp_login_url();
+	/* translators: New site notification email. 1: New site URL, 2: User login, 3: User password or password reset link, 4: Login URL */
 	$message = sprintf( __( "Your new WordPress site has been successfully set up at:
 
 %1\$s
diff --git a/wp-admin/install.php b/wp-admin/install.php
index d22ff6ca86..ed9d06d19c 100644
--- a/wp-admin/install.php
+++ b/wp-admin/install.php
@@ -232,12 +232,16 @@ $mysql_version  = $wpdb->db_version();
 $php_compat     = version_compare( $php_version, $required_php_version, '>=' );
 $mysql_compat   = version_compare( $mysql_version, $required_mysql_version, '>=' ) || file_exists( WP_CONTENT_DIR . '/db.php' );
 
-if ( !$mysql_compat && !$php_compat )
+if ( !$mysql_compat && !$php_compat ) {
+	/* translators: 1: WordPress version number, 2: Minimum required PHP version number, 3: Minimum required MySQL version number, 4: Current PHP version number, 5: Current MySQL version number */
 	$compat = sprintf( __( 'You cannot install because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires PHP version %2$s or higher and MySQL version %3$s or higher. You are running PHP version %4$s and MySQL version %5$s.' ), $wp_version, $required_php_version, $required_mysql_version, $php_version, $mysql_version );
-elseif ( !$php_compat )
+} elseif ( !$php_compat ) {
+	/* translators: 1: WordPress version number, 2: Minimum required PHP version number, 3: Current PHP version number */
 	$compat = sprintf( __( 'You cannot install because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires PHP version %2$s or higher. You are running version %3$s.' ), $wp_version, $required_php_version, $php_version );
-elseif ( !$mysql_compat )
+} elseif ( !$mysql_compat ) {
+	/* translators: 1: WordPress version number, 2: Minimum required MySQL version number, 3: Current MySQL version number */
 	$compat = sprintf( __( 'You cannot install because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires MySQL version %2$s or higher. You are running version %3$s.' ), $wp_version, $required_mysql_version, $mysql_version );
+}
 
 if ( !$mysql_compat || !$php_compat ) {
 	display_header();
diff --git a/wp-admin/nav-menus.php b/wp-admin/nav-menus.php
index a00eb885de..19348c2348 100644
--- a/wp-admin/nav-menus.php
+++ b/wp-admin/nav-menus.php
@@ -518,6 +518,7 @@ if ( ! current_theme_supports( 'menus' ) && ! $num_locations )
 
 if ( ! $locations_screen ) : // Main tab
 	$overview  = '<p>' . __( 'This screen is used for managing your custom navigation menus.' ) . '</p>';
+	/* translators: 1: Widgets admin screen URL, 2 and 3: The name of the default themes */
 	$overview .= '<p>' . sprintf( __( 'Menus can be displayed in locations defined by your theme, even used in sidebars by adding a &#8220;Custom Menu&#8221; widget on the <a href="%1$s">Widgets</a> screen. If your theme does not support the custom menus feature (the default themes, %2$s and %3$s, do), you can learn about adding this support by following the Documentation link to the side.' ), admin_url( 'widgets.php' ), 'Twenty Sixteen', 'Twenty Seventeen' ) . '</p>';
 	$overview .= '<p>' . __( 'From this screen you can:' ) . '</p>';
 	$overview .= '<ul><li>' . __( 'Create, edit, and delete menus' ) . '</li>';
diff --git a/wp-admin/options-discussion.php b/wp-admin/options-discussion.php
index 0f92bfeff4..fefc0d82df 100644
--- a/wp-admin/options-discussion.php
+++ b/wp-admin/options-discussion.php
@@ -107,6 +107,7 @@ $default_comments_page .= '>' . __('last') . '</option><option value="oldest"';
 if ( 'oldest' == get_option('default_comments_page') ) $default_comments_page .= ' selected="selected"';
 $default_comments_page .= '>' . __('first') . '</option></select>';
 
+/* translators: 1: Form field control for number of top level comments per page, 2: Form field control for the 'first' or 'last' page */
 printf( __('Break comments into pages with %1$s top level comments per page and the %2$s page displayed by default'), '</label><label for="comments_per_page"><input name="comments_per_page" type="number" step="1" min="0" id="comments_per_page" value="' . esc_attr(get_option('comments_per_page')) . '" class="small-text" />', $default_comments_page );
 
 ?></label>
diff --git a/wp-admin/revision.php b/wp-admin/revision.php
index 210a336007..c86f78a451 100644
--- a/wp-admin/revision.php
+++ b/wp-admin/revision.php
@@ -74,6 +74,7 @@ default :
 
 	$post_edit_link = get_edit_post_link();
 	$post_title     = '<a href="' . $post_edit_link . '">' . _draft_or_post_title() . '</a>';
+	/* translators: 1: Post title */
 	$h1             = sprintf( __( 'Compare Revisions of &#8220;%1$s&#8221;' ), $post_title );
 	$return_to_post = '<a href="' . $post_edit_link . '">' . __( '&larr; Return to editor' ) . '</a>';
 	$title          = __( 'Revisions' );
diff --git a/wp-admin/update-core.php b/wp-admin/update-core.php
index c66c29cefd..7bc02a7798 100644
--- a/wp-admin/update-core.php
+++ b/wp-admin/update-core.php
@@ -68,12 +68,16 @@ function list_core_update( $update ) {
 				$mysql_compat = version_compare( $mysql_version, $update->mysql_version, '>=' );
 
 			if ( !$mysql_compat && !$php_compat )
+				/* translators: 1: WordPress version number, 2: Minimum required PHP version number, 3: Minimum required MySQL version number, 4: Current PHP version number, 5: Current MySQL version number */
 				$message = sprintf( __('You cannot update because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires PHP version %2$s or higher and MySQL version %3$s or higher. You are running PHP version %4$s and MySQL version %5$s.'), $update->current, $update->php_version, $update->mysql_version, $php_version, $mysql_version );
 			elseif ( !$php_compat )
+				/* translators: 1: WordPress version number, 2: Minimum required PHP version number, 3: Current PHP version number */
 				$message = sprintf( __('You cannot update because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires PHP version %2$s or higher. You are running version %3$s.'), $update->current, $update->php_version, $php_version );
 			elseif ( !$mysql_compat )
+				/* translators: 1: WordPress version number, 2: Minimum required MySQL version number, 3: Current MySQL version number */
 				$message = sprintf( __('You cannot update because <a href="https://codex.wordpress.org/Version_%1$s">WordPress %1$s</a> requires MySQL version %2$s or higher. You are running version %3$s.'), $update->current, $update->mysql_version, $mysql_version );
 			else
+				/* translators: 1: WordPress version number, 2: WordPress version number including locale if necessary */
 				$message = 	sprintf(__('You can update to <a href="https://codex.wordpress.org/Version_%1$s">WordPress %2$s</a> automatically:'), $update->current, $version_string);
 			if ( !$mysql_compat || !$php_compat )
 				$show_buttons = false;
@@ -658,6 +662,8 @@ if ( 'upgrade-core' == $action ) {
 	if ( ! current_user_can( 'update_plugins' ) )
 		wp_die( __( 'Sorry, you are not allowed to update this site.' ) );
 
+	// @TODO
+
 	check_admin_referer('upgrade-core');
 
 	if ( isset( $_GET['plugins'] ) ) {
diff --git a/wp-includes/feed-atom-comments.php b/wp-includes/feed-atom-comments.php
index 5b494a2992..9e62f20ad2 100644
--- a/wp-includes/feed-atom-comments.php
+++ b/wp-includes/feed-atom-comments.php
@@ -28,12 +28,16 @@ do_action( 'rss_tag_pre', 'atom-comments' );
 	?>
 >
 	<title type="text"><?php
-		if ( is_singular() )
+		if ( is_singular() ) {
+			/* translators: Comments feed title. 1: Post title */
 			printf( ent2ncr( __( 'Comments on %s' ) ), get_the_title_rss() );
-		elseif ( is_search() )
+		} elseif ( is_search() ) {
+			/* translators: Comments feed title. 1: Site name, 2: Search query */
 			printf( ent2ncr( __( 'Comments for %1$s searching on %2$s' ) ), get_bloginfo_rss( 'name' ), get_search_query() );
-		else
+		} else {
+			/* translators: Comments feed title. 1: Site name */
 			printf( ent2ncr( __( 'Comments for %s' ) ), get_wp_title_rss() );
+		}
 	?></title>
 	<subtitle type="text"><?php bloginfo_rss('description'); ?></subtitle>
 
@@ -73,8 +77,10 @@ if ( have_comments() ) : while ( have_comments() ) : the_comment();
 				$title = get_the_title($comment_post->ID);
 				/** This filter is documented in wp-includes/feed.php */
 				$title = apply_filters( 'the_title_rss', $title );
+				/* translators: Individual comment title. 1: Post title, 2: Comment author name */
 				printf(ent2ncr(__('Comment on %1$s by %2$s')), $title, get_comment_author_rss());
 			} else {
+				/* translators: Comment author title. 1: Comment author name */
 				printf(ent2ncr(__('By: %s')), get_comment_author_rss());
 			}
 		?></title>
diff --git a/wp-includes/feed-rss2-comments.php b/wp-includes/feed-rss2-comments.php
index af329c5b63..d6ed5ae2b7 100644
--- a/wp-includes/feed-rss2-comments.php
+++ b/wp-includes/feed-rss2-comments.php
@@ -33,12 +33,16 @@ do_action( 'rss_tag_pre', 'rss2-comments' );
 >
 <channel>
 	<title><?php
-		if ( is_singular() )
+		if ( is_singular() ) {
+			/* translators: Comments feed title. 1: Post title */
 			printf( ent2ncr( __( 'Comments on: %s' ) ), get_the_title_rss() );
-		elseif ( is_search() )
+		} elseif ( is_search() ) {
+			/* translators: Comments feed title. 1: Site name, 2: Search query */
 			printf( ent2ncr( __( 'Comments for %1$s searching on %2$s' ) ), get_bloginfo_rss( 'name' ), get_search_query() );
-		else
+		} else {
+			/* translators: Comments feed title. 1: Site name */
 			printf( ent2ncr( __( 'Comments for %s' ) ), get_wp_title_rss() );
+		}
 	?></title>
 	<atom:link href="<?php self_link(); ?>" rel="self" type="application/rss+xml" />
 	<link><?php (is_single()) ? the_permalink_rss() : bloginfo_rss("url") ?></link>
@@ -72,8 +76,10 @@ do_action( 'rss_tag_pre', 'rss2-comments' );
 				$title = get_the_title($comment_post->ID);
 				/** This filter is documented in wp-includes/feed.php */
 				$title = apply_filters( 'the_title_rss', $title );
+				/* translators: Individual comment title. 1: Post title, 2: Comment author name */
 				printf(ent2ncr(__('Comment on %1$s by %2$s')), $title, get_comment_author_rss());
 			} else {
+				/* translators: Comment author title. 1: Comment author name */
 				printf(ent2ncr(__('By: %s')), get_comment_author_rss());
 			}
 		?></title>
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 1bc2aea58e..8593e8c923 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -4087,6 +4087,7 @@ function _doing_it_wrong( $function, $message, $version ) {
 			$message .= ' ' . sprintf( __( 'Please see <a href="%s">Debugging in WordPress</a> for more information.' ),
 				__( 'https://codex.wordpress.org/Debugging_in_WordPress' )
 			);
+			/* translators: Developer debugging message. 1: PHP function name, 2: Explanatory message, 3: Version information message */
 			trigger_error( sprintf( __( '%1$s was called <strong>incorrectly</strong>. %2$s %3$s' ), $function, $message, $version ) );
 		} else {
 			if ( is_null( $version ) ) {
diff --git a/wp-includes/load.php b/wp-includes/load.php
index 42e2b71634..669cf65d0b 100644
--- a/wp-includes/load.php
+++ b/wp-includes/load.php
@@ -128,6 +128,7 @@ function wp_check_php_mysql_versions() {
 		$protocol = wp_get_server_protocol();
 		header( sprintf( '%s 500 Internal Server Error', $protocol ), true, 500 );
 		header( 'Content-Type: text/html; charset=utf-8' );
+		/* translators: 1: Current PHP version number, 2: WordPress version number, 3: Minimum required PHP version number */
 		die( sprintf( __( 'Your server is running PHP version %1$s but WordPress %2$s requires at least %3$s.' ), $php_version, $wp_version, $required_php_version ) );
 	}
 
diff --git a/wp-includes/ms-functions.php b/wp-includes/ms-functions.php
index 0ef1d98337..2e9ca946d9 100644
--- a/wp-includes/ms-functions.php
+++ b/wp-includes/ms-functions.php
@@ -846,7 +846,8 @@ function wpmu_signup_blog_notification( $domain, $path, $title, $user_login, $us
 		 * @param array  $meta       By default, contains the requested privacy setting and lang_id.
 		 */
 		apply_filters( 'wpmu_signup_blog_notification_subject',
-			__( '[%1$s] Activate %2$s' ),
+			/* translators: New site notification email subject. 1: Network name, 2: New site URL */
+			_x( '[%1$s] Activate %2$s', 'New site notification email subject' ),
 			$domain, $path, $title, $user_login, $user_email, $key, $meta
 		),
 		$from_name,
@@ -939,7 +940,8 @@ function wpmu_signup_user_notification( $user_login, $user_email, $key, $meta =
 		 * @param array  $meta       Signup meta data.
 		 */
 		apply_filters( 'wpmu_signup_user_notification_subject',
-			__( '[%1$s] Activate %2$s' ),
+			/* translators: New user notification email subject. 1: Network name, 2: New user login */
+			_x( '[%1$s] Activate %2$s', 'New user notification email subject' ),
 			$user_login, $user_email, $key, $meta
 		),
 		$from_name,
@@ -1202,6 +1204,7 @@ function newblog_notify_siteadmin( $blog_id, $deprecated = '' ) {
 	$siteurl = site_url();
 	restore_current_blog();
 
+	/* translators: New site notification email. 1: Site URL, 2: User IP address, 3: Settings screen URL */
 	$msg = sprintf( __( 'New Site: %1$s
 URL: %2$s
 Remote IP: %3$s
@@ -1244,6 +1247,7 @@ function newuser_notify_siteadmin( $user_id ) {
 	$user = get_userdata( $user_id );
 
 	$options_site_url = esc_url(network_admin_url('settings.php'));
+	/* translators: New user notification email. 1: User login, 2: User IP address, 3: Settings screen URL */
 	$msg = sprintf(__('New User: %1$s
 Remote IP: %2$s
 
@@ -1523,6 +1527,9 @@ We hope you enjoy your new site. Thanks!
 	if ( empty( $current_network->site_name ) )
 		$current_network->site_name = 'WordPress';
 
+	/* translators: New site notification email subject. 1: Network name, 2: New site name */
+	$subject = __( 'New %1$s Site: %2$s' );
+
 	/**
 	 * Filters the subject of the welcome email after site activation.
 	 *
@@ -1530,7 +1537,7 @@ We hope you enjoy your new site. Thanks!
 	 *
 	 * @param string $subject Subject of the email.
 	 */
-	$subject = apply_filters( 'update_welcome_subject', sprintf( __( 'New %1$s Site: %2$s' ), $current_network->site_name, wp_unslash( $title ) ) );
+	$subject = apply_filters( 'update_welcome_subject', sprintf( $subject, $current_network->site_name, wp_unslash( $title ) ) );
 	wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );
 
 	if ( $switched_locale ) {
@@ -1608,6 +1615,9 @@ function wpmu_welcome_user_notification( $user_id, $password, $meta = array() )
 	if ( empty( $current_network->site_name ) )
 		$current_network->site_name = 'WordPress';
 
+	/* translators: New user notification email subject. 1: Network name, 2: New user login */
+	$subject = __( 'New %1$s User: %2$s' );
+
 	/**
 	 * Filters the subject of the welcome email after user activation.
 	 *
@@ -1615,7 +1625,7 @@ function wpmu_welcome_user_notification( $user_id, $password, $meta = array() )
 	 *
 	 * @param string $subject Subject of the email.
 	 */
-	$subject = apply_filters( 'update_welcome_user_subject', sprintf( __( 'New %1$s User: %2$s' ), $current_network->site_name, $user->user_login) );
+	$subject = apply_filters( 'update_welcome_user_subject', sprintf( $subject, $current_network->site_name, $user->user_login) );
 	wp_mail( $user->user_email, wp_specialchars_decode( $subject ), $message, $message_headers );
 
 	if ( $switched_locale ) {
diff --git a/wp-includes/pluggable.php b/wp-includes/pluggable.php
index ef731793ef..3827a53202 100644
--- a/wp-includes/pluggable.php
+++ b/wp-includes/pluggable.php
@@ -1626,6 +1626,7 @@ function wp_notify_moderator($comment_id) {
  		'Currently %s comments are waiting for approval. Please visit the moderation panel:', $comments_waiting), number_format_i18n($comments_waiting) ) . "\r\n";
 	$notify_message .= admin_url( "edit-comments.php?comment_status=moderated#wpbody-content" ) . "\r\n";
 
+	/* translators: Comment moderation notification email subject. 1: Site name, 2: Post title */
 	$subject = sprintf( __('[%1$s] Please moderate: "%2$s"'), $blogname, $post->post_title );
 	$message_headers = '';
 
diff --git a/wp-includes/script-loader.php b/wp-includes/script-loader.php
index cda14254aa..be32073c03 100644
--- a/wp-includes/script-loader.php
+++ b/wp-includes/script-loader.php
@@ -289,6 +289,7 @@ function wp_default_scripts( &$scripts ) {
 		'upload_limit_exceeded' => __('You may only upload 1 file.'),
 		'http_error' => __('HTTP error.'),
 		'upload_failed' => __('Upload failed.'),
+		/* translators: 1: Opening link tag, 2: Closing link tag */
 		'big_upload_failed' => __('Please try uploading this file with the %1$sbrowser uploader%2$s.'),
 		'big_upload_queued' => __('%s exceeds the maximum upload size for the multi-file uploader when used in your browser.'),
 		'io_error' => __('IO error.'),
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 0e88f99808..2e7b4939af 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-beta4-39322';
+$wp_version = '4.7-beta4-39323';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.
diff --git a/wp-includes/wp-db.php b/wp-includes/wp-db.php
index 84dc482a55..74dedd5130 100644
--- a/wp-includes/wp-db.php
+++ b/wp-includes/wp-db.php
@@ -1364,10 +1364,13 @@ class wpdb {
 
 		wp_load_translations_early();
 
-		if ( $caller = $this->get_caller() )
+		if ( $caller = $this->get_caller() ) {
+			/* translators: 1: Database error message, 2: SQL query, 3: Name of the calling function */
 			$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s made by %3$s' ), $str, $this->last_query, $caller );
-		else
+		} else {
+			/* translators: 1: Database error message, 2: SQL query */
 			$error_str = sprintf( __( 'WordPress database error %1$s for query %2$s' ), $str, $this->last_query );
+		}
 
 		error_log( $error_str );
 
@@ -3213,8 +3216,10 @@ class wpdb {
 	public function check_database_version() {
 		global $wp_version, $required_mysql_version;
 		// Make sure the server has the required MySQL version
-		if ( version_compare($this->db_version(), $required_mysql_version, '<') )
+		if ( version_compare($this->db_version(), $required_mysql_version, '<') ) {
+			/* translators: 1: WordPress version number, 2: Minimum required MySQL version number */
 			return new WP_Error('database_version', sprintf( __( '<strong>ERROR</strong>: WordPress %1$s requires MySQL %2$s or higher' ), $wp_version, $required_mysql_version ));
+		}
 	}
 
 	/**
diff --git a/wp-login.php b/wp-login.php
index 28e09ffbe8..db33b703cb 100644
--- a/wp-login.php
+++ b/wp-login.php
@@ -787,10 +787,12 @@ default:
 
 	if ( empty( $_COOKIE[ LOGGED_IN_COOKIE ] ) ) {
 		if ( headers_sent() ) {
+			/* translators: 1: Browser cookie documentation URL, 2: Support forums URL */
 			$user = new WP_Error( 'test_cookie', sprintf( __( '<strong>ERROR</strong>: Cookies are blocked due to unexpected output. For help, please see <a href="%1$s">this documentation</a> or try the <a href="%2$s">support forums</a>.' ),
 				__( 'https://codex.wordpress.org/Cookies' ), __( 'https://wordpress.org/support/' ) ) );
 		} elseif ( isset( $_POST['testcookie'] ) && empty( $_COOKIE[ TEST_COOKIE ] ) ) {
 			// If cookies are disabled we can't log in even with a valid user+pass
+			/* translators: 1: Browser cookie documentation URL */
 			$user = new WP_Error( 'test_cookie', sprintf( __( '<strong>ERROR</strong>: Cookies are blocked or not supported by your browser. You must <a href="%s">enable cookies</a> to use WordPress.' ),
 				__( 'https://codex.wordpress.org/Cookies' ) ) );
 		}