diff --git a/Tests/User/InteractionTest.php b/Tests/User/InteractionTest.php
index d16f37f..0623149 100644
--- a/Tests/User/InteractionTest.php
+++ b/Tests/User/InteractionTest.php
@@ -34,8 +34,7 @@ public function testHttpTransport()
         $interaction = new Interaction(
             new User('123', ['a' => 1]),
             new ItemUUID('abc', 'article'),
-            'buy',
-            10
+            'buy'
         );
 
         $this->assertEquals(
@@ -46,7 +45,7 @@ public function testHttpTransport()
         $this->assertEquals('123', $interaction->getUser()->getId());
         $this->assertEquals('abc', $interaction->getItemUUID()->getId());
         $this->assertEquals('buy', $interaction->getEventName());
-        $this->assertEquals(10, $interaction->getWeight());
+        $this->assertEquals([], $interaction->getMetadata());
     }
 
     /**
@@ -57,13 +56,14 @@ public function testHttpTransportDefaults()
         $interaction = new Interaction(
             new User('123', ['a' => 1]),
             new ItemUUID('abc', 'article'),
-            'buy'
+            'buy',
+            ['field' => 'value']
         );
 
         $this->assertEquals(
             $interaction,
             HttpHelper::emulateHttpTransport($interaction)
         );
-        $this->assertEquals(Interaction::NO_WEIGHT, $interaction->getWeight());
+        $this->assertEquals(['field' => 'value'], $interaction->getMetadata());
     }
 }
diff --git a/User/Interaction.php b/User/Interaction.php
index d037532..9d15d48 100644
--- a/User/Interaction.php
+++ b/User/Interaction.php
@@ -25,13 +25,6 @@
  */
 class Interaction implements HttpTransportable
 {
-    /**
-     * @var int
-     *
-     * No weight
-     */
-    const NO_WEIGHT = 0;
-
     /**
      * @var User
      *
@@ -54,11 +47,11 @@ class Interaction implements HttpTransportable
     private $eventName;
 
     /**
-     * @var int
+     * @var array
      *
-     * Weight
+     * Metadata
      */
-    private $weight;
+    private $metadata;
 
     /**
      * Interaction constructor.
@@ -66,18 +59,18 @@ class Interaction implements HttpTransportable
      * @param User     $user
      * @param ItemUUID $itemUUID
      * @param string   $eventName
-     * @param          $weight
+     * @param array    $metadata
      */
     public function __construct(
         User $user,
         ItemUUID $itemUUID,
         string $eventName,
-        int $weight = self::NO_WEIGHT
+        array $metadata = []
     ) {
         $this->user = $user;
         $this->itemUUID = $itemUUID;
         $this->eventName = $eventName;
-        $this->weight = $weight;
+        $this->metadata = $metadata;
     }
 
     /**
@@ -111,13 +104,13 @@ public function getEventName(): string
     }
 
     /**
-     * Get Weight.
+     * Get Metadata.
      *
-     * @return int
+     * @return array
      */
-    public function getWeight(): int
+    public function getMetadata(): array
     {
-        return $this->weight;
+        return $this->metadata;
     }
 
     /**
@@ -131,9 +124,7 @@ public function toArray(): array
             'user' => $this->user->toArray(),
             'item_uuid' => $this->itemUUID->toArray(),
             'event_name' => $this->eventName,
-            'weight' => self::NO_WEIGHT === $this->weight
-                ? false
-                : $this->weight,
+            'metadata' => $this->metadata,
         ]);
     }
 
@@ -152,7 +143,7 @@ public static function createFromArray(array $array)
             User::createFromArray($array['user']),
             ItemUUID::createFromArray($array['item_uuid']),
             (string) $array['event_name'],
-            (int) ($array['weight'] ?? self::NO_WEIGHT)
+            $array['metadata'] ?? []
         );
     }
 }