diff --git a/smack-core/src/main/java/org/jivesoftware/smack/packet/PacketExtension.java b/smack-core/src/main/java/org/jivesoftware/smack/packet/PacketExtension.java
index 060262349..738c6b8e3 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/packet/PacketExtension.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/packet/PacketExtension.java
@@ -23,6 +23,10 @@ package org.jivesoftware.smack.packet;
  * extended functionality beyond what is in the base XMPP specification. Examples of
  * packet extensions include message events, message properties, and extra presence data.
  * IQ packets cannot contain packet extensions.
+ * <p>
+ * This class is used primarily for extended content in XMPP Stanzas, to act as so called "extension elements". For more
+ * information see <a href="https://tools.ietf.org/html/rfc6120#section-8.4">RFC 6120 § 8.4 Extended Content</a>.
+ * </p>
  *
  * @see DefaultPacketExtension
  * @see org.jivesoftware.smack.provider.PacketExtensionProvider