posts: encrypted_XMPP: update draft

src/pages/posts/2026/encrypted_XMPP.md

@@ -34,6 +34,29 @@ You can check
 In this post, I want to focus specifically on end-to-end encryption
 and the practical aspects of using it.
 
+## Short Glossary
+
+**End-to-end encryption** is a way to keep your chats truly private.
+
+Only you and the person you’re messaging can read the messages.
+Not even the server owner or your carrier has the keys
+needed to decrypt or modify them.
+
+**XMPP** is a protocol made for instant messaging.
+
+The cool thing? The X stands for Extensible,
+which basically means you can add almost any feature through XEPs:
+audio and video calls,
+encryption,
+file transfer,
+sync across devices,
+text markup,
+and even stories!
+
+The ugly thing? The X stands for Extensible,
+which means it’s pretty hard to find two applications
+that support the same subset of XEPs.
+
 ## Trade-offs Between Safety and Convenience
 
 Unfortunately, things that are truly secure are rarely convenient.