diff --git a/core/lib/Drupal/Component/Gettext/PoItem.php b/core/lib/Drupal/Component/Gettext/PoItem.php
index e7edbff91a738d6fd12865790c817f8427690c4b..c268c2c7c151032ac267e376f612cb19a3c0ba14 100644
--- a/core/lib/Drupal/Component/Gettext/PoItem.php
+++ b/core/lib/Drupal/Component/Gettext/PoItem.php
@@ -40,7 +40,7 @@ class PoItem {
   /**
    * Flag indicating if this translation has plurals.
    *
-   * @var boolean
+   * @var bool
    */
   private $_plural;
 
@@ -138,7 +138,7 @@ function setTranslation($translation) {
   /**
    * Set if the translation has plural values.
    *
-   * @param boolean $plural
+   * @param bool $plural
    */
   function setPlural($plural) {
     $this->_plural = $plural;
diff --git a/core/lib/Drupal/Component/Gettext/PoStreamReader.php b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
index 4db52a2a63e06fb00c8b72b1004796165338847e..bb046d251aa8b7f4e4d3512b42209a55956e8379 100644
--- a/core/lib/Drupal/Component/Gettext/PoStreamReader.php
+++ b/core/lib/Drupal/Component/Gettext/PoStreamReader.php
@@ -94,7 +94,7 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
   /**
    * Indicator of whether the stream reading is finished.
    *
-   * @var boolean
+   * @var bool
    */
   private $_finished;
 
diff --git a/core/lib/Drupal/Core/Ajax/AjaxResponse.php b/core/lib/Drupal/Core/Ajax/AjaxResponse.php
index 1bc3d7e0a97a9d396fc139c313f06893d3778cd7..6cd4df5eae9c31a1a5d61198504db9adb169fc89 100644
--- a/core/lib/Drupal/Core/Ajax/AjaxResponse.php
+++ b/core/lib/Drupal/Core/Ajax/AjaxResponse.php
@@ -58,7 +58,7 @@ public function setAttachments(array $attachments) {
    *
    * @param \Drupal\Core\Ajax\CommandInterface $command
    *   An AJAX command object implementing CommandInterface.
-   * @param boolean $prepend
+   * @param bool $prepend
    *   A boolean which determines whether the new command should be executed
    *   before previously added commands. Defaults to FALSE.
    *
diff --git a/core/lib/Drupal/Core/Ajax/SettingsCommand.php b/core/lib/Drupal/Core/Ajax/SettingsCommand.php
index a5a8dc8474875191f5a2cb6d117b25ca1385d741..216ad46875908cce04936008fa001a61cccd4f39 100644
--- a/core/lib/Drupal/Core/Ajax/SettingsCommand.php
+++ b/core/lib/Drupal/Core/Ajax/SettingsCommand.php
@@ -39,7 +39,7 @@ class SettingsCommand implements CommandInterface {
    * By default (FALSE), the settings that are passed to Drupal.attachBehaviors
    * will not include the global drupalSettings.
    *
-   * @var boolean
+   * @var bool
    */
   protected $merge;
 
@@ -48,7 +48,7 @@ class SettingsCommand implements CommandInterface {
    *
    * @param array $settings
    *   An array of key/value pairs of JavaScript settings.
-   * @param boolean $merge
+   * @param bool $merge
    *   Whether the settings should be merged into the global drupalSettings.
    */
   public function __construct(array $settings, $merge = FALSE) {
diff --git a/core/lib/Drupal/Core/Database/Driver/fake/Install/Tasks.php b/core/lib/Drupal/Core/Database/Driver/fake/Install/Tasks.php
index 4ac748711871627c5663eeb0b00d251d08074429..11ed2f31a5cf9661a94460a8f04494199790f455 100644
--- a/core/lib/Drupal/Core/Database/Driver/fake/Install/Tasks.php
+++ b/core/lib/Drupal/Core/Database/Driver/fake/Install/Tasks.php
@@ -22,7 +22,7 @@ class Tasks extends InstallTasks {
    * @TODO Looks like this is needed only if we define $pdoDriver to something valid e.g. mysql.
    * Not sure we need to do that. We may not need this file at all?
    *
-   * @var boolean
+   * @var bool
    */
   protected $error = TRUE;
 
diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
index 64e1511614a97a319f5b795b79e9505e71d6da89..8a70fb0cf2d46705d9a3af9bf32b735705f15b28 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
@@ -30,7 +30,7 @@ class Connection extends DatabaseConnection {
   /**
    * Flag to indicate if the cleanup function in __destruct() should run.
    *
-   * @var boolean
+   * @var bool
    */
   protected $needsCleanup = FALSE;
 
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
index 2bea49fd399129bb9d262831f8b46a5602a37937..b2af0c321022e4dedee5c6e7975bf20d6f29f1be 100644
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
@@ -25,7 +25,7 @@ class Connection extends DatabaseConnection {
    * Version of sqlite lower then 3.6.8 can't use savepoints.
    * See http://www.sqlite.org/releaselog/3_6_8.html
    *
-   * @var boolean
+   * @var bool
    */
   protected $savepointSupport = FALSE;
 
@@ -37,7 +37,7 @@ class Connection extends DatabaseConnection {
   /**
    * Whether or not the active transaction (if any) will be rolled back.
    *
-   * @var boolean
+   * @var bool
    */
   protected $willRollback;
 
@@ -57,7 +57,7 @@ class Connection extends DatabaseConnection {
    * This variable is set to public because Schema needs to
    * access it. However, it should not be manually set.
    *
-   * @var boolean
+   * @var bool
    */
   var $tableDropped = FALSE;
 
diff --git a/core/lib/Drupal/Core/Database/Query/Merge.php b/core/lib/Drupal/Core/Database/Query/Merge.php
index b2ed83948eeda032a3b629b23f7b116f60e2d32e..dfa50e3d2b699497d1030ad54768f306fdd30465 100644
--- a/core/lib/Drupal/Core/Database/Query/Merge.php
+++ b/core/lib/Drupal/Core/Database/Query/Merge.php
@@ -119,7 +119,7 @@ class Merge extends Query implements ConditionInterface {
   /**
    * Flag indicating whether an UPDATE is necessary.
    *
-   * @var boolean
+   * @var bool
    */
   protected $needsUpdate = FALSE;
 
diff --git a/core/lib/Drupal/Core/Database/Query/Select.php b/core/lib/Drupal/Core/Database/Query/Select.php
index 70dc96f0183dcd2b579ed49d253a6f393ed3fc38..d925a07ee922a1a9f1a2487e5b6ae6bbb4893c52 100644
--- a/core/lib/Drupal/Core/Database/Query/Select.php
+++ b/core/lib/Drupal/Core/Database/Query/Select.php
@@ -88,7 +88,7 @@ class Select extends Query implements SelectInterface {
   /**
    * Whether or not this query should be DISTINCT
    *
-   * @var boolean
+   * @var bool
    */
   protected $distinct = FALSE;
 
@@ -114,7 +114,7 @@ class Select extends Query implements SelectInterface {
 
   /**
    * Indicates if preExecute() has already been called.
-   * @var boolean
+   * @var bool
    */
   protected $prepared = FALSE;
 
diff --git a/core/lib/Drupal/Core/Database/Transaction.php b/core/lib/Drupal/Core/Database/Transaction.php
index 68a4fc4ea0c55d1f4506d59bd3f77f0a4dca6ff0..52286e00f6bf660fe89b1b1e6b8ae282d1974a6d 100644
--- a/core/lib/Drupal/Core/Database/Transaction.php
+++ b/core/lib/Drupal/Core/Database/Transaction.php
@@ -38,7 +38,7 @@ class Transaction {
   /**
    * A boolean value to indicate whether this transaction has been rolled back.
    *
-   * @var Boolean
+   * @var bool
    */
   protected $rolledBack = FALSE;
 
diff --git a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
index ec6533d47646d8967258e2d472f15072faab5fbd..96fa0de94cd7df36eac34878546e59fe9e18db63 100644
--- a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
@@ -67,7 +67,7 @@ abstract class EntityDisplayBase extends ConfigEntityBase implements EntityDispl
    * Whether this display is enabled or not. If the entity (form) display
    * is disabled, we'll fall back to the 'default' display.
    *
-   * @var boolean
+   * @var bool
    */
   protected $status;
 
diff --git a/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionInterface.php b/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionInterface.php
index 793279ee065cfd2906cc92f46444d6a4f533ba44..fb4ea5d44dddf62b89ee5f24fa04253a485c4e1e 100644
--- a/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionInterface.php
+++ b/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionInterface.php
@@ -59,7 +59,7 @@ public function validateReferenceableEntities(array $ids);
    *   The current form state.
    * @param array $form
    *   The form.
-   * @param boolean $strict
+   * @param bool $strict
    *   Whether to trigger a form error if an element from $input (eg. an entity)
    *   is not found. Defaults to TRUE.
    *
diff --git a/core/lib/Drupal/Core/Entity/Query/QueryBase.php b/core/lib/Drupal/Core/Entity/Query/QueryBase.php
index f5d36a1e646d3bc8ea9be8f999b05e8f015e5657..4465efd0a380da6cac37860294e9150abc81f1db 100644
--- a/core/lib/Drupal/Core/Entity/Query/QueryBase.php
+++ b/core/lib/Drupal/Core/Entity/Query/QueryBase.php
@@ -40,7 +40,7 @@ abstract class QueryBase implements QueryInterface {
   /**
    * TRUE if this is a count query, FALSE if it isn't.
    *
-   * @var boolean
+   * @var bool
    */
   protected $count = FALSE;
 
diff --git a/core/lib/Drupal/Core/Field/Annotation/FieldType.php b/core/lib/Drupal/Core/Field/Annotation/FieldType.php
index 7a630ab04a1d8d8b33038a782152d7540bac15db..880a2221d22772f8799b8044e6882185086bd919 100644
--- a/core/lib/Drupal/Core/Field/Annotation/FieldType.php
+++ b/core/lib/Drupal/Core/Field/Annotation/FieldType.php
@@ -87,7 +87,7 @@ class FieldType extends DataType {
   /**
    * A boolean stating that fields of this type cannot be created through the UI.
    *
-   * @var boolean
+   * @var bool
    */
   public $no_ui = FALSE;
 
diff --git a/core/lib/Drupal/Core/Path/AliasManager.php b/core/lib/Drupal/Core/Path/AliasManager.php
index d91ad69038df1f3f828c46c6e3958c79d0a4b2ac..d44fc456ba97135072bfc82a5fa228d6ad0d93ca 100644
--- a/core/lib/Drupal/Core/Path/AliasManager.php
+++ b/core/lib/Drupal/Core/Path/AliasManager.php
@@ -38,7 +38,7 @@ class AliasManager implements AliasManagerInterface, CacheDecoratorInterface {
   /**
    * Whether the cache needs to be written.
    *
-   * @var boolean
+   * @var bool
    */
   protected $cacheNeedsWriting = FALSE;
 
diff --git a/core/modules/comment/src/CommentStatisticsInterface.php b/core/modules/comment/src/CommentStatisticsInterface.php
index f73dccd9f6be43bf5d34004aab5fa51b9e49f096..6c0a8a956814555b7bc4d58d25c9e98a3cf0b60c 100644
--- a/core/modules/comment/src/CommentStatisticsInterface.php
+++ b/core/modules/comment/src/CommentStatisticsInterface.php
@@ -32,7 +32,7 @@ public function getRankingInfo();
    *   Array of entities on which commenting is enabled, keyed by id
    * @param string $entity_type
    *   The entity type of the passed entities.
-   * @param boolean $accurate
+   * @param bool $accurate
    *   (optional) Indicates if results must be completely up to date. If set to
    *   FALSE, a replica database will used if available. Defaults to TRUE.
    *
diff --git a/core/modules/comment/src/Tests/CommentNonNodeTest.php b/core/modules/comment/src/Tests/CommentNonNodeTest.php
index 1f3ad3c7f2d0d78ffe61d0f1d46c3dd79ace8e3a..3aefe92d1fd0bef13acc1e0078edb1e161cf8c7c 100644
--- a/core/modules/comment/src/Tests/CommentNonNodeTest.php
+++ b/core/modules/comment/src/Tests/CommentNonNodeTest.php
@@ -174,7 +174,7 @@ function postComment(EntityInterface $entity, $comment, $subject = '', $contact
    *
    * @param \Drupal\comment\CommentInterface $comment
    *   The comment object.
-   * @param boolean $reply
+   * @param bool $reply
    *   Boolean indicating whether the comment is a reply to another comment.
    *
    * @return boolean
@@ -212,7 +212,7 @@ function commentContactInfoAvailable() {
    *   Comment to perform operation on.
    * @param string $operation
    *   Operation to perform.
-   * @param boolean $aproval
+   * @param bool $aproval
    *   Operation is found on approval page.
    */
   function performCommentOperation($comment, $operation, $approval = FALSE) {
diff --git a/core/modules/comment/src/Tests/CommentTestBase.php b/core/modules/comment/src/Tests/CommentTestBase.php
index 12d17c651d93a60ebd95395f87dfd6fed2c6fe16..9aa2e07bffda0304aed9d8115b86aff3278ed469 100644
--- a/core/modules/comment/src/Tests/CommentTestBase.php
+++ b/core/modules/comment/src/Tests/CommentTestBase.php
@@ -179,7 +179,7 @@ public function postComment($entity, $comment, $subject = '', $contact = NULL, $
    *
    * @param \Drupal\comment\CommentInterface $comment
    *   The comment object.
-   * @param boolean $reply
+   * @param bool $reply
    *   Boolean indicating whether the comment is a reply to another comment.
    *
    * @return boolean
@@ -337,7 +337,7 @@ function commentContactInfoAvailable() {
    *   Comment to perform operation on.
    * @param string $operation
    *   Operation to perform.
-   * @param boolean $aproval
+   * @param bool $aproval
    *   Operation is found on approval page.
    */
   function performCommentOperation(CommentInterface $comment, $operation, $approval = FALSE) {
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php b/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
index 987457433f5b433445b18246307bdfdcffd430f2..8bde6ba5ffab27120b2f80dae4769f73544504d7 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
+++ b/core/modules/content_translation/src/Tests/ContentTranslationSettingsTest.php
@@ -208,7 +208,7 @@ function testAccountLanguageSettingsUI() {
    *   The entity type for which to check translatibility.
    * @param string $bundle
    *   The bundle for which to check translatibility.
-   * @param boolean $enabled
+   * @param bool $enabled
    *   TRUE if translatibility should be enabled, FALSE otherwise.
    * @param array $edit
    *   An array of values to submit to the content translation settings page.
diff --git a/core/modules/content_translation/src/Tests/ContentTranslationUITest.php b/core/modules/content_translation/src/Tests/ContentTranslationUITest.php
index 9ed362bd1dcd94de8d4a9380dbce438b511fefe0..0ec3280b3224b51e8281d4d6d6a0b339c40b8ce0 100644
--- a/core/modules/content_translation/src/Tests/ContentTranslationUITest.php
+++ b/core/modules/content_translation/src/Tests/ContentTranslationUITest.php
@@ -28,7 +28,7 @@ abstract class ContentTranslationUITest extends ContentTranslationTestBase {
   /**
    * Whether the behavior of the language selector should be tested.
    *
-   * @var boolean
+   * @var bool
    */
   protected $testLanguageSelector = TRUE;
 
diff --git a/core/modules/editor/src/Annotation/Editor.php b/core/modules/editor/src/Annotation/Editor.php
index 82dc7387e176f572dfaaf8df3741ce98745650e4..58d2450c115c771dae6073ab9a19fb25a201f514 100644
--- a/core/modules/editor/src/Annotation/Editor.php
+++ b/core/modules/editor/src/Annotation/Editor.php
@@ -44,7 +44,7 @@ class Editor extends Plugin {
   /**
    * Whether the editor supports "allowed content only" filtering.
    *
-   * @var boolean
+   * @var bool
    */
   public $supports_content_filtering;
 
diff --git a/core/modules/editor/src/Tests/EditorAdminTest.php b/core/modules/editor/src/Tests/EditorAdminTest.php
index 7ffa1222c2fb3f1646f8649ca5ef3c546dc19633..a39d844109b4176fd25dcd4f215150eb25bed424 100644
--- a/core/modules/editor/src/Tests/EditorAdminTest.php
+++ b/core/modules/editor/src/Tests/EditorAdminTest.php
@@ -152,7 +152,7 @@ protected function selectUnicornEditor() {
    *
    * @param string $format_id
    *   The format machine name.
-   * @param boolean $ponies_too
+   * @param bool $ponies_too
    *   The expected value of the ponies_too setting.
    */
   protected function verifyUnicornEditorConfiguration($format_id, $ponies_too = TRUE) {
diff --git a/core/modules/forum/src/Tests/ForumTest.php b/core/modules/forum/src/Tests/ForumTest.php
index e75507a7e05130bfa7a2cf273f157e2f6b68d986..97c4b38da236f48f200377661f557f3cbef475d0 100644
--- a/core/modules/forum/src/Tests/ForumTest.php
+++ b/core/modules/forum/src/Tests/ForumTest.php
@@ -511,7 +511,7 @@ function testForumWithNewPost() {
    *
    * @param array $forum
    *   A forum array.
-   * @param boolean $container
+   * @param bool $container
    *   TRUE if $forum is a container; FALSE otherwise.
    *
    * @return object
diff --git a/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
index 06a026a4b1e5e7afcfe182d363682ee5bb4cbdae..435907b1a15a23f9044f61c4c17d71544971de3d 100644
--- a/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
+++ b/core/modules/migrate/src/Plugin/migrate/id_map/Sql.php
@@ -84,7 +84,7 @@ class Sql extends PluginBase implements MigrateIdMapInterface {
   /**
    * Whether the plugin is already initialized.
    *
-   * @var boolean
+   * @var bool
    */
   protected $initialized;
 
diff --git a/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
index 6eb87c74e6d172c7335a281b3018c9dc5836bedf..1efbc4a670648a6872e4684fcbc01e3cffd2e7be 100644
--- a/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
@@ -93,7 +93,7 @@ abstract class SourcePluginBase extends PluginBase implements MigrateSourceInter
   /**
    * Whether this instance should cache the source count.
    *
-   * @var boolean
+   * @var bool
    */
   protected $cacheCounts = FALSE;
 
@@ -107,7 +107,7 @@ abstract class SourcePluginBase extends PluginBase implements MigrateSourceInter
   /**
    * Whether this instance should not attempt to count the source.
    *
-   * @var boolean
+   * @var bool
    */
   protected $skipCount = FALSE;
 
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/File.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/File.php
index 9401decb62e5d66a78a31bb08d04a973d652efe8..ff51c620915dffe1786d9ecc3836592e3b4c8f42 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/File.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/File.php
@@ -36,7 +36,7 @@ class File extends DrupalSqlBase {
   /**
    * Flag for private or public file storage.
    *
-   * @var boolean
+   * @var bool
    */
   protected $isPublic;
 
diff --git a/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
index e56c40733cf96fd463d3d67e45f4fc0154a77e37..a95baded2617ddc9dd3b5a314233d0ce177810b3 100644
--- a/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -91,7 +91,7 @@ abstract class TestBase {
   /**
    * TRUE if verbose debugging is enabled.
    *
-   * @var boolean
+   * @var bool
    */
   public $verbose;
 
@@ -260,7 +260,7 @@ abstract class TestBase {
   /**
    * Whether to die in case any test assertion fails.
    *
-   * @var boolean
+   * @var bool
    *
    * @see run-tests.sh
    */
diff --git a/core/modules/system/src/Tests/KeyValueStore/StorageTestBase.php b/core/modules/system/src/Tests/KeyValueStore/StorageTestBase.php
index b59828e6b39bf955942a260118222def5d490a86..cb82a72c3361621befb24fbd8f173fb3d3d00640 100644
--- a/core/modules/system/src/Tests/KeyValueStore/StorageTestBase.php
+++ b/core/modules/system/src/Tests/KeyValueStore/StorageTestBase.php
@@ -31,7 +31,7 @@ abstract class StorageTestBase extends KernelTestBase {
   /**
    * Whether we are using an expirable key/value store.
    *
-   * @var boolean
+   * @var bool
    */
   protected $factory = 'keyvalue';
 
diff --git a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
index 4e6b967823ef9c81505e3bda3a2e30666eec2586..7edf50cc2e585a7a3b732d3a523f69241ccfef8f 100644
--- a/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/NumberTest.php
@@ -31,7 +31,7 @@ class NumberTest extends UnitTestCase {
    *   The value argument for Number::validStep().
    * @param numeric $step
    *   The step argument for Number::validStep().
-   * @param boolean $expected
+   * @param bool $expected
    *   Expected return value from Number::validStep().
    */
   public function testValidStep($value, $step, $expected) {
@@ -51,7 +51,7 @@ public function testValidStep($value, $step, $expected) {
    *   The step argument for Number::validStep().
    * @param numeric $offset
    *   The offset argument for Number::validStep().
-   * @param boolean $expected
+   * @param bool $expected
    *   Expected return value from Number::validStep().
    */
   public function testValidStepOffset($value, $step, $offset, $expected) {
diff --git a/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php b/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php
index b9861c28d88ddde34048cd659154c66e9222e5cd..724d875e9571098977f7592609c4cb7ccbfcfe26 100644
--- a/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/UnicodeTest.php
@@ -466,7 +466,7 @@ public function providerTestTruncateBytes() {
    *
    * @param string $text
    *   The text to validate.
-   * @param boolean $expected
+   * @param bool $expected
    *   The expected return value from Unicode::validateUtf8().
    * @param string $message
    *   The message to display on failure.