What is Container ?
A container is a lightweight, standalone package that encapsulates application code and all of its dependencies so the application can run in any environment. Containers are considered as lightweight virtualization technology. They are created from a container image.
What is Container Image ?
A container image is a read-only, static file that includes executable code. It can be roughly considered as similar to template that is used to create something concrete that runs, which in our case if containers. Containers are created from container images. Image contains various layers which serves as a base for upper layers.
What is Docker ?
Docker is a containerization platform developed by a company called Docker Inc. It provides a runtime environment to run containers and interact with them. Docker uses some technologies like CGroups, Namespaces, etc to create an isolated containers.