Terminology
In the last section, we used a lot of Docker-specific jargon which might be confusing to some. So before we go further, let me clarify some terminology that is used frequently in the Docker ecosystem.
- Images - The blueprints of our application which form the basis of containers. In the demo above, we used the
docker pull
command to download the busybox image. - Containers - Created from Docker images and run the actual application. We create a container using
docker run
which we did using the busybox image that we downloaded. A list of running containers can be seen using thedocker ps
command. - Docker Daemon - The background service running on the host that manages building, running and distributing Docker containers. The daemon is the process that runs in the operating system which clients talk to.
- Docker Client - The command line tool that allows the user to interact with the daemon. More generally, there can be other forms of clients too - such as Kitematic which provide a GUI to the users.
- Docker Hub - A registry of Docker images. You can think of the registry as a directory of all available Docker images. If required, one can host their own Docker registries and can use them for pulling images.