diff --git a/core/lib/Drupal/Core/Language/Language.php b/core/lib/Drupal/Core/Language/Language.php
index 29b8852..4e25563 100644
--- a/core/lib/Drupal/Core/Language/Language.php
+++ b/core/lib/Drupal/Core/Language/Language.php
@@ -70,7 +70,9 @@ class Language implements LanguageInterface {
   /**
    * The language negotiation method used when a language was detected.
    *
-   * @var bool
+   * The method ID, for example, LanguageNegotiatorInterface::METHOD_ID.
+   *
+   * @var string
    *
    * @see language_types_initialize()
    */
@@ -88,7 +90,7 @@ class Language implements LanguageInterface {
   public $locked = FALSE;
 
   /**
-   * Language constructor builds the default language object.
+   * Builds the default language object.
    *
    * @param array $options
    *   The properties used to construct the language.
diff --git a/core/lib/Drupal/Core/Language/LanguageInterface.php b/core/lib/Drupal/Core/Language/LanguageInterface.php
index 2d6fac2..6c099a4 100644
--- a/core/lib/Drupal/Core/Language/LanguageInterface.php
+++ b/core/lib/Drupal/Core/Language/LanguageInterface.php
@@ -97,7 +97,10 @@
   const DIRECTION_RTL = 1;
 
   /**
-   * Get the name of the Language object.
+   * Gets the name of the Language object.
+   *
+   * @return string
+   *   The human readable English name of the Language.
    */
   public function getName();
 
@@ -105,6 +108,7 @@ public function getName();
    * Sets the name.
    *
    * @param string $name
+   *   The human readable English name of the Language.
    *
    * @return $this
    */
@@ -114,13 +118,15 @@ public function setName($name);
    * Gets the ID (language code).
    *
    * @return string
+   *   The langcode.
    */
   public function getId();
 
   /**
    * Sets the ID (language code).
    *
-   * @param string $langcode
+   * @param string $id
+   *   The langcode.
    *
    * @return $this
    */
@@ -137,7 +143,8 @@ public function getDirection();
   /**
    * Sets the direction of the language.
    *
-   * @param string $direction
+   * @param int $direction
+   *   Either self::DIRECTION_LTR or self::DIRECTION_RTL.
    *
    * @return $this
    */
@@ -145,6 +152,10 @@ public function setDirection($direction);
 
   /**
    * Gets the weight of the language.
+   *
+   * @return int
+   *   The weight, used to order languages with larger positive weights sinking
+   *   items toward the bottom of lists.
    */
   public function getWeight();
 
@@ -152,15 +163,18 @@ public function getWeight();
    * Sets the weight of the language.
    *
    * @param int $weight
+   *   The weight, used to order languages with larger positive weights sinking
+   *   items toward the bottom of lists.
    *
    * @return $this
    */
   public function setWeight($weight);
 
   /**
-   * Gets whether this language is the default language.
+   * Returns whether this language is the default language.
    *
    * @return bool
+   *   Whether the language is the default language.
    */
   public function isDefault();
 
@@ -168,6 +182,7 @@ public function isDefault();
    * Sets whether this language is the default language.
    *
    * @param bool $default
+   *   True if it is the default language.
    *
    * @return $this
    */
@@ -175,6 +190,9 @@ public function setDefault($default);
 
   /**
    * Gets the language negotiation method ID for this language.
+   *
+   * @return string
+   *   The method ID, for example, LanguageNegotiatorInterface::METHOD_ID.
    */
   public function getNegotiationMethodId();
 
@@ -182,8 +200,10 @@ public function getNegotiationMethodId();
    * Sets the language negotiation method ID for this language.
    *
    * @param string $method_id
+   *   The method ID, for example, LanguageNegotiatorInterface::METHOD_ID.
    *
    * @return $this
    */
   public function setNegotiationMethodId($method_id);
+
 }
diff --git a/core/tests/Drupal/Tests/Core/Language/LanguageUnitTest.php b/core/tests/Drupal/Tests/Core/Language/LanguageUnitTest.php
index 11635ec..466ad87 100644
--- a/core/tests/Drupal/Tests/Core/Language/LanguageUnitTest.php
+++ b/core/tests/Drupal/Tests/Core/Language/LanguageUnitTest.php
@@ -13,6 +13,9 @@
 
 /**
  * Tests \Drupal\Core\Language\Language.
+ *
+ * @group Drupal
+ * @group Language
  */
 class LanguageUnitTest extends UnitTestCase {
 
@@ -35,13 +38,15 @@ public static function getInfo() {
   }
 
   /**
-   * {@inheritdoc
+   * {@inheritdoc}
    */
   public function setUp() {
     $this->language = new Language();
   }
 
   /**
+   * Tests name getter and setter methods.
+   *
    * @covers \Drupal\Core\Language\Language::getName()
    * @covers \Drupal\Core\Language\Language::setName()
    */
@@ -52,6 +57,8 @@ public function testGetName() {
   }
 
   /**
+   * Tests langcode ID getter and setter methods.
+   *
    * @covers \Drupal\Core\Language\Language::getId()
    * @covers \Drupal\Core\Language\Language::setId()
    */
@@ -62,6 +69,8 @@ public function testGetLangcode() {
   }
 
   /**
+   * Tests direction getter and setter methods.
+   *
    * @covers \Drupal\Core\Language\Language::getDirection()
    * @covers \Drupal\Core\Language\Language::setDirection()
    */
@@ -72,6 +81,8 @@ public function testGetDirection() {
   }
 
   /**
+   * Tests isDefault() and default setter.
+   *
    * @covers \Drupal\Core\Language\Language::isDefault()
    * @covers \Drupal\Core\Language\Language::setDefault()
    */
@@ -82,6 +93,8 @@ public function testIsDefault() {
   }
 
   /**
+   * Tests negotiationMethodId getter and setter methods.
+   *
    * @covers \Drupal\Core\Language\Language::getNegotiationMethodId()
    * @covers \Drupal\Core\Language\Language::setNegotiationMethodId()
    */
@@ -90,4 +103,5 @@ public function testGetNegotiationMethodId() {
     $this->assertSame(spl_object_hash($this->language), spl_object_hash($this->language->setNegotiationMethodId($method_id)));
     $this->assertSame($method_id, $this->language->getNegotiationMethodId());
   }
+
 }