If you are just getting started in learning about the many protocols of IoT devices, one of the most popular is MQTT.
MQTT is the winner because of its very lightweight and secure process for how it sends data. I could go in detail but I am sure the MQTT Organization website does a better job than I can.
You can easily start sending data between one device to another on your home network using MQTT. You can setup one of your computers as a server or could use an external free server like mqtt.eclipse.org to demonstrate how data flows in from one device to the other.
We have created simple scripts that you can run on any OS to simulate an IoT device sending data to the topic of your choice. Using mqtt.eclipse.org as the server and a lightweight paho-mqtt python library as the MQTT client for the device.
Please feel free to comment here or contact us if you need further help or have any questions!