Unique IDs are great but sometimes you might want to use something like Reading 1, Reading 2 instead of "-Lt-FPU_zdiCjHXnrWwP", not that that's not a great name for your pet, especially if you have 3.2 trillion pets and each of them need a unique ID. Sometimes though it's nice to call your pet "Horseyface" and not -Lt-FPU_zdiCjHXnrWwP. This tutorial shows you how to send sensor data to firebase without the ugly ID and name it whatever you want. eg. Measurement-1, Measurement-2 etc.