diff --git a/core/lib/Drupal/Core/Field/FieldConfigBase.php b/core/lib/Drupal/Core/Field/FieldConfigBase.php
index fc18ccc40a0..b58f49dc698 100644
--- a/core/lib/Drupal/Core/Field/FieldConfigBase.php
+++ b/core/lib/Drupal/Core/Field/FieldConfigBase.php
@@ -490,6 +490,12 @@ abstract class FieldConfigBase extends ConfigEntityBase implements FieldConfigIn
    * {@inheritdoc}
    */
   public function getDataType() {
+    // This object serves as data definition for field item lists, thus
+    // the correct data type is 'list'. This is not to be confused with
+    // the config schema type, 'field_config_base', which is used to
+    // describe the schema of the configuration backing this objects.
+    // @see \Drupal\Core\Field\FieldItemList
+    // @see \Drupal\Core\TypedData\DataDefinitionInterface
     return 'list';
   }