In this chapter, we discussed several ways that internet-connected devices can talk to each other. We dove into the MQTT protocol and discussed how its PubSub interface and abstractions made it a great choice for projects on our Pi. Then, we built a bot that communicated with the outside world using a button and let the outside world communicate with it via the AdafruitIO dashboard and IFTTT. Finally, we built a social media notification bot using AdafruitIO integration into IFTTT.