Achilleus has a brief primer on Docker:
Now that we know, some basic definitions. It’s time we ask the main question! Why do I care?
There are many reasons you might wanna use Docker. I will give my perspective on why I started to learn about Docker.
I had to test my Kafka producers and consumers locally instead of deploying my code in DEV/QA even before I was sure things are working fine but also be sure that the same code, when deployed in other environments, should behave the same.
There are a few really good reasons for containers and testing is one of them.