diff --git a/Readme.md b/Readme.md
index bf83541..0ec5ce7 100644
--- a/Readme.md
+++ b/Readme.md
@@ -6,5 +6,7 @@ Run your own AIM chat server, managing users and groups. Hook up a vintage clien
 
 - [x] Accept and start negotiating a connection with a client
 - [x] Perform username/password authentication
-- [ ] Set up basic services
+- [x] Set up basic services
+  - [ ] Online/offline status for users
+  - [ ] Send IM back and forth
 - [ ] The rest of the owl
diff --git a/src/services/0x04-ICBM.ts b/src/services/0x04-ICBM.ts
index 52af05f..04f7e55 100644
--- a/src/services/0x04-ICBM.ts
+++ b/src/services/0x04-ICBM.ts
@@ -133,6 +133,8 @@ export default class ICBM extends BaseService {
         const messageText = messageTLV.payload.slice(startOfMessageFragment + 8, startOfMessageFragment + 8 + lengthOfMessageText).toString();
         console.log('The user said:', messageText);
 
+        // The client usually wants a response that the server got the message. It checks that the message
+        // back has the same message ID that was sent and the user it was sent to.
         if (wantsAck) {
           const sender = this.communicator.user?.username || "";
           const msgIdBuffer = Buffer.alloc(32);