Docker's main components

Docker uses three main components:

• Docker containers: Isolated user-space environments running the same or different applications and sharing the same host OS. Containers are created from Docker images.
• Docker images: Docker templates that include application libraries and applications. Images are used to create containers and you can bring up containers immediately. You can create and update your own custom images as well as download build images from Docker's public registry.
• Docker registries: This is a images store. Docker registries can be public or private, meaning that you can work with images available over the internet or create your own registry for internal purposes. One popular public Docker registry is Docker Hub, discussed later in this chapter.