Docker Engine is responsible for creating containers, pulling images etc, i.e. Docker Engine does all backbone work. Docker Engine consists of the following components :

• Daemon
• Container D
• Run C

When the user runs docker … command on the host machine, it is first fetched to Docker Client. When Docker Client retrieves that command, it sends an API call to Docker Engine. Daemon is responsible for receiving requests from the Docker Client. Depending on the type of command, Daemon forwards it either to Container D or Run C component. Creating Docker Container commands go to Run C, whereas all other commands go to Container D.