What is the difference between a Docker image and a container?
docker, docker-container, docker-image
Solution
An instance of an image is called a container. You have an image, which is a set of layers as you describe. If you start this image, you have a running container of this image. You can have many running containers of the same image.
You can see all your images with `docker images` whereas you can see your running containers with `docker ps` (and you can see all containers with `docker ps -a`).
So a running instance of an image is a container.
Problem
When using Docker, we start with a base image. We boot it up, create changes and those changes are saved in layers forming another image. So eventually I have an image for my PostgreSQL instance and an image for my web application, changes to which keep on being persisted. What is a container?