diff --git a/core/modules/dblog/dblog.admin.inc b/core/modules/dblog/dblog.admin.inc
index b2da7ed..61a355e 100644
--- a/core/modules/dblog/dblog.admin.inc
+++ b/core/modules/dblog/dblog.admin.inc
@@ -6,10 +6,12 @@
  */
 
 /**
- * Menu callback; displays a listing of log messages.
+ * Page callback: Displays a listing of dblog messages.
  *
- * Messages are truncated at 56 chars. Full-length message could be viewed at
- * the message details page.
+ * Messages are truncated at 56 chars. Full-length message can be viewed in
+ * their entirity on the message details page (admin/reports/event/%).
+ *
+ * @see dblog_menu()
  */
 function dblog_overview() {
   $filter = dblog_build_filter_query();
@@ -79,12 +81,15 @@ function dblog_overview() {
 }
 
 /**
- * Menu callback; generic function to display a page of the most frequent events.
+ * Page callback: Shows the most frequent log messages of a given event type.
+ *
+ * Messages are not truncated on this page because events detailed herein do not
+ * have links to a detailed view.
  *
- * Messages are not truncated because events from this page have no detail view.
+ * @param string $type
+ *   Type of database log events to display (e.g. 'search').
  *
- * @param $type
- *   type of dblog events to display.
+ * @see dblog_menu()
  */
 function dblog_top($type) {
 
@@ -125,7 +130,12 @@ function dblog_top($type) {
 }
 
 /**
- * Menu callback; displays details about a log message.
+ * Page callback: Displays details about a specific database log message.
+ *
+ * @param int $id
+ *   Unique watchdog event ID.
+ *
+ * @see dblog_menu()
  */
 function dblog_event($id) {
   $severity = watchdog_severity_levels();
@@ -182,7 +192,10 @@ function dblog_event($id) {
 }
 
 /**
- * Build query for dblog administration filters based on session.
+ * Builds a query for database log administration filters based on session.
+ *
+ * @return array
+ *   An associative array with keys 'where' and 'args'.
  */
 function dblog_build_filter_query() {
   if (empty($_SESSION['dblog_overview_filter'])) {
@@ -211,9 +224,16 @@ function dblog_build_filter_query() {
   );
 }
 
-
 /**
- * List dblog administration filters that can be applied.
+ * Creates a list of database log administration filters that can be applied.
+ *
+ * @return array
+ *   Two-dimensional array with 'type' and 'severity' top-level keys, each of
+ *   which is an array with the following keys:
+ *   - title: Title of the filter.
+ *   - where: The filter condition.
+ *   - options: Types of watchdog messages or severity levels.
+ *   If no records exist in the table, the 'type' element will not be returned.
  */
 function dblog_filters() {
   $filters = array();
@@ -240,9 +260,9 @@ function dblog_filters() {
 }
 
 /**
- * Returns HTML for a log message.
+ * Returns an HTML string for a database log event.
  *
- * @param $variables
+ * @param array $variables
  *   An associative array containing:
  *   - event: An object with at least the message and variables properties.
  *   - link: (optional) Format message as link, event->wid is required.
@@ -272,11 +292,11 @@ function theme_dblog_message($variables) {
 }
 
 /**
- * Return form for dblog administration filters.
+ * Form constructor for the dblog filter form.
  *
- * @ingroup forms
- * @see dblog_filter_form_submit()
  * @see dblog_filter_form_validate()
+ * @see dblog_filter_form_submit()
+ * @ingroup forms
  */
 function dblog_filter_form($form) {
   $filters = dblog_filters();
@@ -314,12 +334,13 @@ function dblog_filter_form($form) {
       '#value' => t('Reset')
     );
   }
-
   return $form;
 }
 
 /**
- * Validate result from dblog administration filter form.
+ * Form validation handler for dblog_filter_form().
+ *
+ * @see dblog_filter_form_submit()
  */
 function dblog_filter_form_validate($form, &$form_state) {
   if ($form_state['values']['op'] == t('Filter') && empty($form_state['values']['type']) && empty($form_state['values']['severity'])) {
@@ -328,7 +349,9 @@ function dblog_filter_form_validate($form, &$form_state) {
 }
 
 /**
- * Process result from dblog administration filter form.
+ * Form submission handler for dblog_filter_form().
+ *
+ * @see dblog_filter_form_validate()
  */
 function dblog_filter_form_submit($form, &$form_state) {
   $op = $form_state['values']['op'];
@@ -349,10 +372,12 @@ function dblog_filter_form_submit($form, &$form_state) {
 }
 
 /**
- * Return form for dblog clear button.
+ * Form constructor for the dblog clear log form.
+ *
+ * This form allows the user to clear the dblog table of event messages.
  *
- * @ingroup forms
  * @see dblog_clear_log_submit()
+ * @ingroup forms
  */
 function dblog_clear_log_form($form) {
   $form['dblog_clear'] = array(
@@ -367,12 +392,13 @@ function dblog_clear_log_form($form) {
     '#value' => t('Clear log messages'),
     '#submit' => array('dblog_clear_log_submit'),
   );
-
   return $form;
 }
 
 /**
- * Submit callback: clear database with log messages.
+ * Submission handler for dblog_clear_log_form().
+ *
+ * @see dblog_clear_log_form()
  */
 function dblog_clear_log_submit() {
   $_SESSION['dblog_overview_filter'] = array();
diff --git a/core/modules/dblog/dblog.module b/core/modules/dblog/dblog.module
index e92fcbd..c9c8235 100644
--- a/core/modules/dblog/dblog.module
+++ b/core/modules/dblog/dblog.module
@@ -6,9 +6,9 @@ use Drupal\Core\Database\Database;
  * @file
  * System monitoring and logging for administrators.
  *
- * The dblog module monitors your site and keeps a list of
- * recorded events containing usage and performance data, errors,
- * warnings, and similar operational information.
+ * The Database Logging module monitors your site and keeps a list of recorded
+ * events containing usage and performance data, errors, warnings, and similar
+ * operational information.
  *
  * @see watchdog()
  */
@@ -98,10 +98,10 @@ function dblog_init() {
 /**
  * Implements hook_cron().
  *
- * Remove expired log messages and flood control events.
+ * Controls the size of the log table, paring it to 'dblog_row_limit' messages.
  */
 function dblog_cron() {
-  // Cleanup the watchdog table.
+  // Cleanup the database log table.
   $row_limit = variable_get('dblog_row_limit', 1000);
 
   // For row limit n, get the wid of the nth row in descending wid order.
@@ -123,6 +123,12 @@ function dblog_cron() {
   }
 }
 
+/**
+ * Gathers a list of uniquely defined database log message types.
+ *
+ * @return array
+ *   List of uniquely defined database log message types.
+ */
 function _dblog_get_message_types() {
   $types = array();
 
@@ -137,7 +143,7 @@ function _dblog_get_message_types() {
 /**
  * Implements hook_watchdog().
  *
- * Note some values may be truncated for database column size restrictions.
+ * Note: Some values may be truncated to meet database column size restrictions.
  */
 function dblog_watchdog(array $log_entry) {
   // The user object may not exist in all conditions, so 0 is substituted if needed.
@@ -160,7 +166,7 @@ function dblog_watchdog(array $log_entry) {
 }
 
 /**
- * Implements hook_form_FORM_ID_alter().
+ * Implements hook_form_FORM_ID_alter() for system_logging_settings().
  */
 function dblog_form_system_logging_settings_alter(&$form, $form_state) {
   $form['dblog_row_limit'] = array(
diff --git a/core/modules/dblog/dblog.test b/core/modules/dblog/dblog.test
index e3a997e..678772d 100644
--- a/core/modules/dblog/dblog.test
+++ b/core/modules/dblog/dblog.test
@@ -2,9 +2,12 @@
 
 /**
  * @file
- * Tests for dblog.module.
+ * Tests for Database Logging module.
  */
 
+/**
+ * Tests the Database Logging module functionality.
+ */
 class DBLogTestCase extends DrupalWebTestCase {
   protected $profile = 'standard';
 
@@ -20,7 +23,7 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Enable modules and create users with specific permissions.
+   * Enables modules and creates users with specific permissions.
    */
   function setUp() {
     parent::setUp('dblog', 'poll');
@@ -30,7 +33,11 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Login users, create dblog events, and test dblog functionality through the admin and user interfaces.
+   * Tests Database Logging module functionality through interfaces.
+   *
+   * First logs in users, then creates database log events, and finally tests
+   * Database Logging module functionality through both the admin and user
+   * interfaces.
    */
   function testDBLog() {
     // Login the admin user.
@@ -48,9 +55,10 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Verify setting of the dblog row limit.
+   * Verifies setting of the database log row limit.
    *
-   * @param integer $count Log row limit.
+   * @param int $row_limit
+   *   The row limit.
    */
   private function verifyRowLimit($row_limit) {
     // Change the dblog row limit.
@@ -68,9 +76,10 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Verify cron applies the dblog row limit.
+   * Verifies that cron correctly applies the database log row limit.
    *
-   * @param integer $count Log row limit.
+   * @param int $row_limit
+   *   The row limit.
    */
   private function verifyCron($row_limit) {
     // Generate additional log entries.
@@ -81,19 +90,20 @@ class DBLogTestCase extends DrupalWebTestCase {
 
     // Run cron job.
     $this->cronRun();
-    // Verify dblog row count equals row limit plus one because cron adds a record after it runs.
+    // Verify dblog row count equals row limit plus one because cron adds a
+    // record after it runs.
     $count = db_query('SELECT COUNT(wid) FROM {watchdog}')->fetchField();
     $this->assertTrue($count == $row_limit + 1, t('Dblog row count of @count equals row limit of @limit plus one', array('@count' => $count, '@limit' => $row_limit)));
   }
 
   /**
-   * Generate dblog entries.
+   * Generates a number of random database log events.
    *
-   * @param integer $count
-   *   Number of log entries to generate.
-   * @param $type
+   * @param int $count
+   *   Number of watchdog entries to generate.
+   * @param string $type
    *   The type of watchdog entry.
-   * @param $severity
+   * @param int $severity
    *   The severity of the watchdog entry.
    */
   private function generateLogEntries($count, $type = 'custom', $severity = WATCHDOG_NOTICE) {
@@ -120,9 +130,10 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Verify the logged in user has the desired access to the various dblog nodes.
+   * Verifies logged in user has desired access to various database log nodes.
    *
-   * @param integer $response HTTP response code.
+   * @param int $response
+   *   HTTP response code.
    */
   private function verifyReports($response = 200) {
     $quote = ''';
@@ -164,7 +175,7 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Verify events.
+   * Generates and then verifies various types of events.
    */
   private function verifyEvents() {
     // Invoke events.
@@ -179,14 +190,14 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Generate and verify user events.
-   *
+   * Generates and then verifies some user events.
    */
   private function doUser() {
     // Set user variables.
     $name = $this->randomName();
     $pass = user_password();
-    // Add user using form to generate add user event (which is not triggered by drupalCreateUser).
+    // Add user using form to generate add user event (which is not triggered by
+    // drupalCreateUser).
     $edit = array();
     $edit['name'] = $name;
     $edit['mail'] = $name . '@example.com';
@@ -198,7 +209,8 @@ class DBLogTestCase extends DrupalWebTestCase {
     // Retrieve user object.
     $user = user_load_by_name($name);
     $this->assertTrue($user != NULL, t('User @name was loaded', array('@name' => $name)));
-    $user->pass_raw = $pass; // Needed by drupalLogin.
+    // pass_raw property is needed by drupalLogin.
+    $user->pass_raw = $pass;
     // Login user.
     $this->drupalLogin($user);
     // Logout user.
@@ -213,7 +225,7 @@ class DBLogTestCase extends DrupalWebTestCase {
 
     // Login the admin user.
     $this->drupalLogin($this->big_user);
-    // Delete user.
+    // Delete user created at start of this test.
     // We need to POST here to invoke batch_process() in the internal browser.
     $this->drupalPost('user/' . $user->uid . '/cancel', array('user_cancel_method' => 'user_cancel_reassign'), t('Cancel account'));
 
@@ -221,9 +233,10 @@ class DBLogTestCase extends DrupalWebTestCase {
     $this->drupalGet('admin/reports/dblog');
     $this->assertResponse(200);
 
-    // Verify events were recorded.
+    // Verify that the expected events were recorded.
     // Add user.
-    // Default display includes name and email address; if too long then email is replaced by three periods.
+    // Default display includes name and email address; if too long, the email
+    // address is replaced by three periods.
     $this->assertLogMessage(t('New user: %name (%email).', array('%name' => $name, '%email' => $user->mail)), t('DBLog event was recorded: [add user]'));
     // Login user.
     $this->assertLogMessage(t('Session opened for %name.', array('%name' => $name)), t('DBLog event was recorded: [login user]'));
@@ -261,9 +274,10 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Generate and verify node events.
+   * Generates and then verifies some node events.
    *
-   * @param string $type Content type.
+   * @param string $type
+   *   A node type (e.g. 'article', 'page' or 'poll').
    */
   private function doNode($type) {
     // Create user.
@@ -272,7 +286,8 @@ class DBLogTestCase extends DrupalWebTestCase {
     // Login user.
     $this->drupalLogin($user);
 
-    // Create node using form to generate add content event (which is not triggered by drupalCreateNode).
+    // Create node using form to generate add content event (which is not
+    // triggered by drupalCreateNode).
     $edit = $this->getContent($type);
     $langcode = LANGUAGE_NOT_SPECIFIED;
     $title = $edit["title"];
@@ -301,32 +316,35 @@ class DBLogTestCase extends DrupalWebTestCase {
     $this->drupalGet('admin/reports/dblog');
     $this->assertResponse(200);
 
-    // Verify events were recorded.
-    // Content added.
+    // Verify node events were recorded.
+    // Was node content added?
     $this->assertLogMessage(t('@type: added %title.', array('@type' => $type, '%title' => $title)), t('DBLog event was recorded: [content added]'));
-    // Content updated.
+    // Was node content updated?
     $this->assertLogMessage(t('@type: updated %title.', array('@type' => $type, '%title' => $title)), t('DBLog event was recorded: [content updated]'));
-    // Content deleted.
+    // Was node content deleted?
     $this->assertLogMessage(t('@type: deleted %title.', array('@type' => $type, '%title' => $title)), t('DBLog event was recorded: [content deleted]'));
 
     // View dblog access-denied report node.
     $this->drupalGet('admin/reports/access-denied');
     $this->assertResponse(200);
-    // Access denied.
+    // Verify 'access denied' event was recorded.
     $this->assertText(t('admin/reports/dblog'), t('DBLog event was recorded: [access denied]'));
 
     // View dblog page-not-found report node.
     $this->drupalGet('admin/reports/page-not-found');
     $this->assertResponse(200);
-    // Page not found.
+    // Verify 'page not found' event was recorded.
     $this->assertText(t('node/@nid', array('@nid' => $node->nid)), t('DBLog event was recorded: [page not found]'));
   }
 
   /**
-   * Create content based on content type.
+   * Creates random content based on node content type.
+   *
+   * @param string $type
+   *   Node content type (e.g. 'article').
    *
-   * @param string $type Content type.
-   * @return array Content.
+   * @return array
+   *   Random content needed by various node types.
    */
   private function getContent($type) {
     $langcode = LANGUAGE_NOT_SPECIFIED;
@@ -350,10 +368,13 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Create content update based on content type.
+   * Creates random content as an update based on node content type.
+   *
+   * @param string $type
+   *   Node content type (e.g. 'article').
    *
-   * @param string $type Content type.
-   * @return array Content.
+   * @return array
+   *   Random content needed by various node types.
    */
   private function getContentUpdate($type) {
     switch ($type) {
@@ -375,15 +396,18 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Login an admin user, create dblog event, and test clearing dblog functionality through the admin interface.
+   * Tests the addition and clearing of log events through the admin interface.
+   *
+   * First logs in an admin user, then creates database log event, and finally
+   * tests the clearing dblog functionality through the admin interface.
    */
   protected function testDBLogAddAndClear() {
     global $base_root;
-    // Get a count of how many watchdog entries there are.
+    // Get a count of how many watchdog entries already exist.
     $count = db_query('SELECT COUNT(*) FROM {watchdog}')->fetchField();
     $log = array(
       'type'        => 'custom',
-      'message'     => 'Log entry added to test the doClearTest clear down.',
+      'message'     => 'Log entry added to test the testDBLogAddAndClear clearing logic.',
       'variables'   => array(),
       'severity'    => WATCHDOG_NOTICE,
       'link'        => NULL,
@@ -395,11 +419,11 @@ class DBLogTestCase extends DrupalWebTestCase {
     );
     // Add a watchdog entry.
     dblog_watchdog($log);
-    // Make sure the table count has actually incremented.
+    // Make sure the table count has actually been incremented.
     $this->assertEqual($count + 1, db_query('SELECT COUNT(*) FROM {watchdog}')->fetchField(), t('dblog_watchdog() added an entry to the dblog :count', array(':count' => $count)));
     // Login the admin user.
     $this->drupalLogin($this->big_user);
-    // Now post to clear the db table.
+    // Now post to clear the database table.
     $this->drupalPost('admin/reports/dblog', array(), t('Clear log messages'));
     // Count rows in watchdog that previously related to the deleted user.
     $count = db_query('SELECT COUNT(*) FROM {watchdog}')->fetchField();
@@ -407,15 +431,17 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Test the dblog filter on admin/reports/dblog.
+   * Tests the database log filter functionality.
+   *
+   * Path: admin/reports/dblog
    */
   protected function testFilter() {
     $this->drupalLogin($this->big_user);
 
-    // Clear log to ensure that only generated entries are found.
+    // Clear log to ensure that only generated entries will be found.
     db_delete('watchdog')->execute();
 
-    // Generate watchdog entries.
+    // Generate 9 random watchdog entries.
     $type_names = array();
     $types = array();
     for ($i = 0; $i < 3; $i++) {
@@ -431,10 +457,10 @@ class DBLogTestCase extends DrupalWebTestCase {
       }
     }
 
-    // View the dblog.
+    // View the dblog page.
     $this->drupalGet('admin/reports/dblog');
 
-    // Confirm all the entries are displayed.
+    // Confirm that all the entries are displayed.
     $count = $this->getTypeCount($types);
     foreach ($types as $key => $type) {
       $this->assertEqual($count[$key], $type['count'], 'Count matched');
@@ -460,8 +486,8 @@ class DBLogTestCase extends DrupalWebTestCase {
       $this->assertEqual(array_sum($count), $type_count, 'Count matched');
     }
 
-    // Set filter to match each of the three type attributes and confirm the
-    // number of entries displayed.
+    // Set filter to match each of the two filter-type attributes and confirm
+    // correct number of entries are displayed.
     foreach ($types as $key => $type) {
       $edit = array(
         'type[]' => array($type['type']),
@@ -472,17 +498,21 @@ class DBLogTestCase extends DrupalWebTestCase {
       $count = $this->getTypeCount($types);
       $this->assertEqual(array_sum($count), $type['count'], 'Count matched');
     }
-    
+
     // Clear all logs and make sure the confirmation message is found.
     $this->drupalPost('admin/reports/dblog', array(), t('Clear log messages'));
     $this->assertText(t('Database log cleared.'), t('Confirmation message found'));
   }
 
   /**
-   * Get the log entry information form the page.
+   * Gets the database log event information from the browser page.
    *
-   * @return
-   *   List of entries and their information.
+   * @return array
+   *   List of dblog events where each event is an array with following keys:
+   *   - severity: (int) A dblog severity constant.
+   *   - type: (string) The type of dblog event.
+   *   - message: (string) The message for this dblog event.
+   *   - user: (string) The user associated with this dblog event.
    */
   protected function getLogEntries() {
     $entries = array();
@@ -501,11 +531,12 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Get the count of entries per type.
+   * Gets the count of database log entries by database log event type.
    *
-   * @param $types
+   * @param array $types
    *   The type information to compare against.
-   * @return
+   *
+   * @return array
    *   The count of each type keyed by the key of the $types array.
    */
   protected function getTypeCount(array $types) {
@@ -523,11 +554,12 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Get the watchdog severity constant corresponding to the CSS class.
+   * Gets the watchdog severity constant corresponding to the CSS class.
    *
-   * @param $class
+   * @param string $class
    *   CSS class attribute.
-   * @return
+   *
+   * @return int|null
    *   The watchdog severity constant or NULL if not found.
    */
   protected function getSeverityConstant($class) {
@@ -554,11 +586,12 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Extract the text contained by the element.
+   * Extracts the text contained by the XHTML element.
    *
-   * @param $element
+   * @param SimpleXMLElement $element
    *   Element to extract text from.
-   * @return
+   *
+   * @return string
    *   Extracted text.
    */
   protected function asText(SimpleXMLElement $element) {
@@ -569,21 +602,24 @@ class DBLogTestCase extends DrupalWebTestCase {
   }
 
   /**
-   * Assert messages appear on the log overview screen.
+   * Confirms that a log message appears on the database log overview screen.
+   *
+   * Path: /admin/reports/dblog
    *
    * This function should be used only for admin/reports/dblog page, because it
-   * check for the message link text truncated to 56 characters. Other dblog
-   * pages have no detail links so contains a full message text.
+   * checks for the message link text truncated to 56 characters. Other log
+   * pages have no detail links so they contain the full message text.
    *
-   * @param $log_message
-   *   The message to check.
-   * @param $message
+   * @param string $log_message
+   *   The database log message to check.
+   * @param string $message
    *   The message to pass to simpletest.
    */
   protected function assertLogMessage($log_message, $message) {
     $message_text = truncate_utf8(filter_xss($log_message, array()), 56, TRUE, TRUE);
-    // After filter_xss() HTML entities should be converted to their characters
-    // because assertLink() uses this string in xpath() to query DOM.
+    // After filter_xss(), HTML entities should be converted to their character
+    // equivalents because assertLink() uses this string in xpath() to query the
+    // Document Object Model (DOM).
     $this->assertLink(html_entity_decode($message_text), 0, $message);
   }
 }