diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index c2457761e062490f4f04e3b469b47ac179fe0074..694113fb57e67101817ed4fb249fd10444577d68 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -224,7 +224,12 @@ class DrupalKernel implements DrupalKernelInterface, TerminableInterface {
   protected static $isEnvironmentInitialized = FALSE;
 
   /**
-   * The site directory.
+   * The site path directory.
+   *
+   * Site path is relative to the app root directory.
+   * Usually defined as "sites/default".
+   *
+   * By default, drupal uses sites/default.
    *
    * @var string
    */
diff --git a/core/lib/Drupal/Core/DrupalKernelInterface.php b/core/lib/Drupal/Core/DrupalKernelInterface.php
index dfd00f20170ec8eef732ca2438859e592fa014f9..f42e8eec6fb3fc88b11d9e7269737d0e56dd15b6 100644
--- a/core/lib/Drupal/Core/DrupalKernelInterface.php
+++ b/core/lib/Drupal/Core/DrupalKernelInterface.php
@@ -74,7 +74,9 @@ public function getContainer();
   public function getCachedContainerDefinition();
 
   /**
-   * Set the current site path.
+   * Set the current site path directory.
+   *
+   * Format: "folder-name/child-folder" usually uses "sites/default".
    *
    * @param string $path
    *   The current site path.
@@ -85,10 +87,10 @@ public function getCachedContainerDefinition();
   public function setSitePath($path);
 
   /**
-   * Get the site path.
+   * Gets the site path directory.
    *
    * @return string
-   *   The current site path.
+   *   The current site path directory.
    */
   public function getSitePath();