What are the components of Docker and how they related to each other?

Docker consists of several main components:

• Docker Server (also called Docker Daemon, Docker Server, "dockerd") - The background process that manages Docker containers and handles container objects. The daemon listens for requests received from the Docker Engine API.
• Docker Client (also called Docker CLI (Command Line Interface), "docker") - The command line tool that allows users to interact with Docker Engine.
• Docker API (Application Programming Interface) - Interfaces that programs can use to talk to and instruct the Docker Server.
• Docker Images - A Docker image is a binary file used to build containers. Images are used to store and ship applications.
• Docker Containers - A Docker container is a deployed instance of an application that runs on the Docker Engine in an encapsulated environment.
• Docker Registries - Repository Websites for Docker images. Docker clients connect to registries to download ("pull") images for use or upload ("push") images that they have built. Registries can be public or private. Two main public registries are Docker Hub and Docker Cloud. Docker Hub is the default registry where Docker looks for images.

These components are work together as shown in this Docker architecture diagram:

Sometimes, Docker Server, Docker Client and Docker API are referred together as Docker Engine.

Docker Engine allows you to run mulitple virtual operating systems on a single hosting system. But those virtual systems must match the architecture of the hosting system.

In other words, Linux Docker containers can only run on a Linux hosting system. Windows Docker containers can only run on a Windows hosting system.

⇒ Install Docker CE on CentOS

⇐ What Is Docker

⇑ Introduction to Docker

⇑⇑ Docker Container Platform - Tutorials