Containers have become integral to every phase in the lifecycle of application development. Production grade orchestration tools such as Kubernetes have been built to manage them and container platforms like Docker are becoming commonplace in both testing and development. Web tutorials on how to build and manage simple Docker images abound! But what are containers exactly and why have they become so essential to the DevOps ecosystem? This talk is for those curious minds who want to look below the surface and really understand the mechanics of a technique that has actually been around longer than you may think. Where did Docker come from? What about other projects in the container ecosystem - are there alternatives? What does a Docker image actually look like on the filesystem? How do Docker image layers work? What are cgroups? How are system resources allocated and managed and are there any gotchas that you should be aware of as a Java developer? What about security? How can JFrog Container Registry help me manage my Docker images? After this talk, you will have a solid understanding of the what, how & why of virtualized container technology.