Questions 

1. How do you send a message using Mosquitto?
2. How do you subscribe to messages using Mosquitto?
3. What does -t stand for when using the Mosquitto commands?
4. What does -m stand for when sending messages via MQTT?
5. Have a look at the explore page of shiftr.io (https://shiftr.io/explore). Here, you will find public namespaces from other people. How do they use shiftr.io and MQTT? Can you tell by looking at the namespaces, topics, and connected clients? How do other people organize their topics? Which structure do they use?

6. Try opening a few other tabs and sending messages from each of them. Open another one and experiment with subscriptions. Do you remember how they work? You can use slashes to create sub-topics (for example, /test/sub-topic), or use wildcards to subscribe to multiple topics at once (for example, /test/#), which will get an update once...